Arizona v. United States

[Argued April 25, 2012. Decided June 25, 2012, on certiorari to the United States Court of Appeals for the Ninth Circuit, 641 F. 3d 339 (2011), which had affirmed a preliminary injunction issued by the District of Arizona, 703 F. Supp. 2d 980 (2010). Disposition: “641 F. 3d 339, affirmed in part, reversed in part, and remanded.”]

[The Reporter’s line-up: “KENNEDY, J., delivered the opinion of the Court, in which ROBERTS, C. J., and GINSBURG, BREYER, and SOTOMAYOR, JJ., joined. SCALIA, J., THOMAS, J., and ALITO, J., filed opinions concurring in part and dissenting in part. KAGAN, J., took no part in the consideration or decision of the case.” No numerical vote is printed, and no single number would be honest anyway: eight Justices participated and the alignment changes with each provision.]

[The vote, provision by provision. §3 (state alien-registration crime): pre-empted, Kennedy, Roberts, Ginsburg, Breyer, Sotomayor and Alito — six. §5(C) (crime for an unauthorized alien to seek or perform work): pre-empted, the same five without Alito — five, with Scalia, Thomas and Alito the other way. §6 (warrantless arrest on probable cause of a removable offense): pre-empted, the same five. §2(B) (the mandatory status check): the injunction was improper, and every participating Justice agreed on that result. Justice Alito’s road-map paragraphs below state his own position across all four; they are the cleanest map in the case.]

[This case carries real U.S. Reports pin cites. The star markers — \*401 and the like — mark the first word of that page of volume 567. Where a marked omission drops text, the marker on the next kept passage carries the page forward. The opinion of the Court is continuous from *392 to *416.]

[What to watch for. First, three doctrines in one case. §3 falls by field preemption at 401: “Where Congress occupies an entire field, as it has in the field of alien registration, even complementary state regulation is impermissible.” §5(C) and §6 fall by obstacle preemption, at 406 and 410, both citing Hines at 67. No provision falls by impossibility — the phrase “physical impossibility” appears once in the whole case, in the doctrinal recital at 399, quoting Florida Lime & Avocado Growers. Watch the Court keep the categories separate, and then watch Justice Scalia say at 433 that the §5(C) analysis is “a classic description not of conflict pre-emption but of field pre-emption.”

Second, what happened to §2(B). It is the provision everyone remembers and the one most often misdescribed. The phrase “not pre-empted” never appears in the opinion of the Court; the Court’s strongest statement is conditional — §2(B) “likely would survive pre-emption — at least absent some showing that it has other consequences that are adverse to federal law and its objectives” (414). The ground of decision is at 415: the challenge came before the law took effect, without a state-court construction, and so “the United States cannot prevail in its current challenge.” The Court adds that its opinion “does not foreclose other pre-emption and constitutional challenges.” That is a ripeness-flavored holding, not an endorsement.

Third, Hines four ways. Every Justice who writes relies on the same handful of pages of a 1941 opinion — 312 U. S. at 66–67, 70, 72, 74, and Justice Stone’s dissent at 75–76 — and each derives a different holding. Kennedy at 401 and 403 reads it as field preemption (and cites Garamendi and Pennsylvania v. Nelson to say so). Scalia at 429 says “that case did not, as the Court believes, establish a ‘field pre-emption’” and answers with Stone’s dissent. Thomas at 439 says Hines “at most holds that federal law pre-empts the States from creating additional registration requirements.” Alito at 450 concedes that “the Court largely spoke in the language of field pre-emption” and joins the Court on §3 for that reason alone. Read the four passages against each other and against the Hines note in this module.

Fourth, the presumption. The word “presumption” does not appear once in the opinion of the Court. The Court recites the Rice formulation a single time, at 400 — “courts should assume that ‘the historic police powers of the States’ are not superseded ‘unless that was the clear and manifest purpose of Congress,’” citing Rice and Wyeth — and then never returns to it. Justice Alito uses “clear and manifest” eight times, precisely because he thinks the Court abandoned it.

Fifth, Justice Thomas is the bridge to Wyeth. His opinion runs a thousand words and is given entire. It opens by quoting his own Wyeth concurrence at 588 and closes by citing it twice at 604 for the proposition that “pre-emptive effect is to be given to congressionally enacted laws, not to judicially divined legislative purposes.” Three years after Wyeth, the objection has not moved an inch.]*

*392 JUSTICE KENNEDY delivered the opinion of the Court.

To address pressing issues related to the large number of aliens within its borders who do not have a lawful right to *393 be in this country, the State of Arizona in 2010 enacted a statute called the Support Our Law Enforcement and Safe Neighborhoods Act. The law is often referred to as S. B. 1070, the version introduced in the State Senate. See also H. B. 2162, 49th Leg., 2d Reg. Sess. (2010) (amending S. B. 1070). Its stated purpose is to “discourage and deter the unlawful entry and presence of aliens and economic activity by persons unlawfully present in the United States.” Note following Ariz. Rev. Stat. Ann. § 11-1051 (West 2012). The law’s provisions establish an official state policy of “attrition through enforcement.” Ibid. The question before the Court is whether federal law pre-empts and renders invalid four separate provisions of the state law.

I

The United States filed this suit against Arizona, seeking to enjoin S. B. 1070 as pre-empted. Four provisions of the law are at issue here. Two create new state offenses. Section 3 makes failure to comply with federal alien-registration requirements a state misdemeanor. Ariz. Rev. Stat. Ann. § 13-1509 (West Supp. 2011). Section 5, in relevant part, *394 makes it a misdemeanor for an unauthorized alien to seek or engage in work in the State; this provision is referred to as § 5(C). See § 13-2928(C). Two other provisions give specific arrest authority and investigative duties with respect to certain aliens to state and local law enforcement officers. Section 6 authorizes officers to arrest without a warrant a person “the officer has probable cause to believe… has committed any public offense that makes the person removable from the United States.” § 13-3883(A)(5). Section 2(B) provides that officers who conduct a stop, detention, or arrest must in some circumstances make efforts to verify the person’s immigration status with the Federal Government. See § 11-1051(B) (West 2012).

The United States District Court for the District of Arizona issued a preliminary injunction preventing the four provisions at issue from taking effect. 703 F. Supp. 2d 980, 1008 (2010). The Court of Appeals for the Ninth Circuit affirmed. 641 F. 3d 339, 366 (2011). It agreed that the United States had established a likelihood of success on its pre-emption claims. The Court of Appeals was unanimous in its conclusion that §§ 3 and 5(C) were likely pre-empted. Judge Bea dissented from the decision to uphold the preliminary injunction against §§ 2(B) and 6. This Court granted certiorari to resolve important questions concerning the interaction of state and federal power with respect to the law of immigration and alien status. 565 U. S. 1092 (2011).

II

A

The Government of the United States has broad, undoubted power over the subject of immigration and the status of aliens. See Toll v. Moreno, 458 U. S. 1, 10 (1982); see generally S. Legomsky & C. Rodriguez, Immigration and Refugee Law and Policy 115-132 (5th ed. 2009). This authority rests, in part, on the National Government’s constitutional power to “establish an uniform Rule of *395 Naturalization,” Art. I, § 8, cl. 4, and its inherent power as sovereign to control and conduct relations with foreign nations, see Toll, supra, at 10 (citing United States v. Curtiss-Wright Export Corp., 299 U. S. 304, 318 (1936)).

The federal power to determine immigration policy is well settled. Immigration policy can affect trade, investment, tourism, and diplomatic relations for the entire Nation, as well as the perceptions and expectations of aliens in this country who seek the full protection of its laws. See, e. g., Brief for United Mexican States as Amicus Curiae; see also Harisiades v. Shaughnessy, 342 U. S. 580, 588-589 (1952). Perceived mistreatment of aliens in the United States may lead to harmful reciprocal treatment of American citizens abroad. See Brief for Madeleine K. Albright et al. as Amici Curiae 24-30.

It is fundamental that foreign countries concerned about the status, safety, and security of their nationals in the United States must be able to confer and communicate on this subject with one national sovereign, not the 50 separate States. See Chy Lung v. Freeman, 92 U. S. 275, 279-280 (1876); see also The Federalist No. 3, p. 39 (C. Rossiter ed. 2003) (J. Jay) (observing that federal power would be necessary in part because “bordering States… under the impulse of sudden irritation, and a quick sense of apparent interest or injury” might take action that would undermine foreign relations). This Court has reaffirmed that “[o]ne of the most important and delicate of all international relationships… has to do with the protection of the just rights of a country’s own nationals when those nationals are in another country.” Hines v. Davidowitz, 312 U. S. 52, 64 (1941).

Federal governance of immigration and alien status is extensive and complex. Congress has specified categories of aliens who may not be admitted to the United States. See 8 U. S. C. § 1182. Unlawful entry and unlawful reentry into the country are federal offenses. §§ 1325, 1326. Once here, aliens are required to register with the Federal Government *396 and to carry proof of status on their person. See §§ 1301-1306. Failure to do so is a federal misdemeanor. §§ 1304(e), 1306(a). Federal law also authorizes States to deny nonciti-zens a range of public benefits, § 1622; and it imposes sanctions on employers who hire unauthorized workers, § 1324a.

Congress has specified which aliens may be removed from the United States and the procedures for doing so. Aliens may be removed if they were inadmissible at the time of entry, have been convicted of certain crimes, or meet other criteria set by federal law. See § 1227. Removal is a civil, not criminal, matter. A principal feature of the removal system is the broad discretion exercised by immigration officials. See Brief for Former Commissioners of the United States Immigration and Naturalization Service as Amici Curiae 8-13 (hereinafter Brief for Former INS Commissioners). Federal officials, as an initial matter, must decide whether it makes sense to pursue removal at all. If removal proceedings commence, aliens may seek asylum and other discretionary relief allowing them to remain in the country or at least to leave without formal removal. See § 1229a(c)(4); see also, e.g., §§ 1158 (asylum), 1229b (cancellation of removal), 1229c (voluntary departure).

[Parts II-B’s opening paragraphs, which recite the burdens Arizona attributes to unlawful immigration — apprehension and seizure statistics, and the record accounts of crime and property damage near the border — are omitted. Justice Scalia calls this passage “the prologue,” post, at 436. So is a paragraph on enforcement discretion and a paragraph describing the roles of CBP, ICE and USCIS.]

*397 B

*398 These concerns are the background for the formal legal analysis that follows. The issue is whether, under preemption principles, federal law permits Arizona to implement the state-law provisions in dispute.

III

Federalism, central to the constitutional design, adopts the principle that both the National and State Governments have elements of sovereignty the other is bound to respect. See Gregory v. Ashcroft, 501 U. S. 452, 457 (1991); U. S. Term Limits, Inc. v. Thornton, 514 U. S. 779, 838 (1995) (Kennedy, J., concurring). From the existence of two sovereigns *399 follows the possibility that laws can be in conflict or at cross-purposes. The Supremacy Clause provides a clear rule that federal law “shall be the supreme Law of the Land; and the Judges in every state shall be bound thereby, any Thing in the Constitution or Laws of any state to the Contrary notwithstanding.” Art. VI, cl. 2. Under this principle, Congress has the power to pre-empt state law. See Crosby v. National Foreign Trade Council, 530 U. S. 363, 372 (2000); Gibbons v. Ogden, 9 Wheat. 1, 210-211 (1824). There is no doubt that Congress may withdraw specified powers from the States by enacting a statute containing an express preemption provision. See, e. g., Chamber of Commerce of United States of America v. Whiting, 563 U. S. 582, 592 (2011).

State law must also give way to federal law in at least two other circumstances. First, the States are precluded from regulating conduct in a field that Congress, acting within its proper authority, has determined must be regulated by its exclusive governance. See Gade v. National Solid Wastes Management Assn., 505 U. S. 88, 115 (1992) (Souter, J., dissenting). The intent to displace state law altogether can be inferred from a framework of regulation “so pervasive… that Congress left no room for the States to supplement it” or where there is a “federal interest… so dominant that the federal system will be assumed to preclude enforcement of state laws on the same subject.” Rice v. Santa Fe Elevator Corp., 331 U. S. 218, 230 (1947); see English v. General Elec. Co., 496 U. S. 72, 79 (1990).

Second, state laws are pre-empted when they conflict with federal law. Crosby, supra, at 372. This includes cases where “compliance with both federal and state regulations is a physical impossibility,” Florida Lime & Avocado Growers, Inc. v. Paul, 373 U. S. 132, 142-143 (1963), and those instances where the challenged state law “stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress,” Hines, 312 U. S., at 67; see also *400 Crosby, supra, at 373 (“What is a sufficient obstacle is a matter of judgment, to be informed by examining the federal statute as a whole and identifying its purpose and intended effects”). In pre-emption analysis, courts should assume that “the historic police powers of the States” are not superseded “unless that was the clear and manifest purpose of Congress.” Rice, supra, at 230; see Wyeth v. Levine, 555 U. S. 555, 565 (2009).

The four challenged provisions of the state law each must be examined under these pre-emption principles.

IV

A

Section 3

Section 3 of S. B. 1070 creates a new state misdemeanor. It forbids the “willful failure to complete or carry an alien registration document… in violation of 8 United States Code § 1304(e) or 1306(a).” Ariz. Rev. Stat. Ann. § 13— 1509(A). In effect, § 3 adds a state-law penalty for conduct proscribed by federal law. The United States contends that this state enforcement mechanism intrudes on the field of alien registration, a field in which Congress has left no room for States to regulate. See Brief for United States 27, 31.

The Court discussed federal alien-registration requirements in Hines, supra. In 1940, as international conflict spread, Congress added to federal immigration law a “complete system for alien registration.” Id., at 70. The new federal law struck a careful balance. It punished an alien’s willful failure to register but did not require aliens to carry identification cards. There were also limits on the sharing of registration records and fingerprints. The Court found that Congress intended the federal plan for registration to be a “single integrated and all-embracing system.” Id., at 74. Because this “complete scheme… for the registration of aliens” touched on foreign relations, it did not allow the States to “curtail or complement” federal law or to “enforce *401 additional or auxiliary regulations.” Id., at 66-67. As a consequence, the Court ruled that Pennsylvania could not enforce its own alien-registration program. See id., at 59, 74.

The present regime of federal regulation is not identical to the statutory framework considered in Hines, but it remains comprehensive. Federal law now includes a requirement that aliens carry proof of registration. 8 U. S. C. § 1304(e). Other aspects, however, have stayed the same. Aliens who remain in the country for more than 30 days must apply for registration and be fingerprinted. Compare § 1302(a) with § 452(a) (1940 ed.). Detailed information is required, and any change of address has to be reported to the Federal Government. Compare §§ 1304(a), 1305(a) (2006 ed.) with §§ 455(a), 456 (1940 ed.). The statute continues to provide penalties for the willful failure to register. Compare § 1306(a) (2006 ed.) with §457 (1940 ed.).

The framework enacted by Congress leads to the conclusion here, as it did in Hines, that the Federal Government has occupied the field of alien registration. See American Ins. Assn. v. Garamendi, 539 U. S. 396, 419, n. 11 (2003) (characterizing Hines as a field pre-emption case); Pennsylvania v. Nelson, 350 U. S. 497, 504 (1956) (same); see also Dinh, Reassessing the Law of Preemption, 88 Geo. L. J. 2085, 2098-2099, 2107 (2000) (same). The federal statutory directives provide a full set of standards governing alien registration, including the punishment for noncompliance. It was designed as a “‘harmonious whole.’” Hines, supra, at 72. Where Congress occupies an entire field, as it has in the field of alien registration, even complementary state regulation is impermissible. Field pre-emption reflects a congressional decision to foreclose any state regulation in the area, even if it is parallel to federal standards. See Silkwood v. Kerr-McGee Corp., 464 U. S. 238, 249 (1984).

Federal law makes a single sovereign responsible for maintaining a comprehensive and unified system to keep track of *402 aliens within the Nation’s borders. If §3 of the Arizona statute were valid, every State could give itself independent authority to prosecute federal registration violations, “diminish[ing] the [Federal Government] ⅛ control over enforcement” and “detracting] from the ‘integrated scheme of regulation’ created by Congress.” Wisconsin Dept. of Industry v. Gould Inc., 475 U. S. 282, 288-289 (1986). Even if a State may make violation of federal law a crime in some instances, it cannot do so in a field (like the field of alien registration) that has been occupied by federal law. See California v. Zook, 336 U. S. 725, 730-731, 733 (1949); see also In re Loney, 134 U. S. 372, 375-376 (1890) (States may not impose their own punishment for perjury in federal courts).

Arizona contends that § 3 can survive pre-emption because the provision has the same aim as federal law and adopts its substantive standards. This argument not only ignores the basic premise of field pre-emption—that States may not enter, in any respect, an area the Federal Government has reserved for itself—but also is unpersuasive on its own terms. Permitting the State to impose its own penalties for the federal offenses here would conflict with the careful framework Congress adopted. Cf. Buckman Co. v. Plaintiffs’ Legal Comm., 531 U. S. 341, 347-348 (2001) (States may not impose their own punishment for fraud on the Food and Drug Administration); Wisconsin Dept., supra, at 288 (States may not impose their own punishment for repeat violations of the National Labor Relations Act). Were §3 to come into force, the State would have the power to bring criminal charges against individuals for violating a federal law even in circumstances where federal officials in charge of the comprehensive scheme determine that prosecution would frustrate federal policies.

There is a further intrusion upon the federal scheme. Even where federal authorities believe prosecution is appropriate, there is an inconsistency between § 3 and federal law *403 with respect to penalties. Under federal law, the failure to carry registration papers is a misdemeanor that may be punished by a fine, imprisonment, or a term of probation. See 8 U. S. C. § 1304(e) (2006 ed.); 18 U. S. C. § 3561. State law, by contrast, rules out probation as a possible sentence (and also eliminates the possibility of a pardon). See Ariz. Rev. Stat. Ann. § 13-1509(D). This state framework of sanctions creates a conflict with the plan Congress put in place. See Wisconsin Dept., supra, at 286 (“[C]onflict is imminent whenever two separate remedies are brought to bear on the same activity” (internal quotation marks omitted)).

These specific conflicts between state and federal law simply underscore the reason for field pre-emption. As it did in Hines, the Court now concludes that, with respect to the subject of alien registration, Congress intended to preclude States from “complement[ing] the federal law, or enforcing] additional or auxiliary regulations.” 312 U. S., at 66-67. Section 3 is pre-empted by federal law.

B

Section 5(C)

Unlike §3, which replicates federal statutory requirements, §5(C) enacts a state criminal prohibition where no federal counterpart exists. The provision makes it a state misdemeanor for “an unauthorized alien to knowingly apply for work, solicit work in a public place or perform work as an employee or independent contractor” in Arizona. Ariz. Rev. Stat. Ann. §13-2928(C). Violations can be punished by a $2,500 fine and incarceration for up to six months. See § 13-2928(F); see also §§ 13-707(A)(1) (West 2010); 13-802(A); 13-902(A)(5) (West Supp. 2011). The United States contends that the provision upsets the balance struck by the Immigration Reform and Control Act of 1986 (IRCA) and must be pre-empted as an obstacle to the federal plan of regulation and control.

*404 When there was no comprehensive federal program regulating the employment of unauthorized aliens, this Court found that a State had authority to pass its own laws on the subject. In 1971, for example, California passed a law imposing civil penalties on the employment of aliens who were “not entitled to lawful residence in the United States if such employment would have an adverse effect on lawful resident workers.” 1971 Cal. Stats. ch. 1442, § 1(a). The law was upheld against a pre-emption challenge in De Canas v. Bica, 424 U. S. 351 (1976). De Canas recognized that “States possess broad authority under their police powers to regulate the employment relationship to protect workers within the State.” Id., at 356. At that point, however, the Federal Government had expressed no more than “a peripheral concern with [the] employment of illegal entrants.” Id., at 360; see Whiting, 563 U. S., at 588.

Current federal law is substantially different from the regime that prevailed when De Canas was decided. Congress enacted IRCA as a comprehensive framework for “combating the employment of illegal aliens.” Hoffman Plastic Compounds, Inc. v. NLRB, 535 U. S. 137, 147 (2002). The law makes it illegal for employers to knowingly hire, recruit, refer, or continue to employ unauthorized workers. See 8 U. S. C. §§ 1324a(a)(1)(A), (a)(2). It also requires every employer to verify the employment authorization status of prospective employees. See §§ 1324a(a)(1)(B), (b); 8 CFR § 274a.2(b) (2012). These requirements are enforced through criminal penalties and an escalating series of civil penalties tied to the number of times an employer has violated the provisions. See 8 U. S. C. §§ 1324a(e)(4), (f); 8 CFR § 274a.10.

This comprehensive framework does not impose federal criminal sanctions on the employee side (i. e., penalties on aliens who seek or engage in unauthorized work). Under federal law some civil penalties are imposed instead. With certain exceptions, aliens who accept unlawful employment *405 are not eligible to have their status adjusted to that of a lawful permanent resident. See 8 U. S. C. §§ 1255(c)(2), (c)(8). Aliens also may be removed from the country for having engaged in unauthorized work. See § 1227(a)(1) (C)(i); 8 CFR § 214.1(e). In addition to specifying these civil consequences, federal law makes it a crime for unauthorized workers to obtain employment through fraudulent means. See 18 U. S. C. § 1546(b). Congress has made clear, however, that any information employees submit to indicate their work status “may not be used” for purposes other than prosecution under specified federal criminal statutes for fraud, perjury, and related conduct. See 8 U. S. C. §§ 1324a(b)(5), (d)(2)(F)-(G).

The legislative background of IRCA underscores the fact that Congress made a deliberate choice not to impose criminal penalties on aliens who seek, or engage in, unauthorized employment. A commission established by Congress to study immigration policy and to make recommendations concluded these penalties would be “unnecessary and unworkable.” U. S. Immigration Policy and the National Interest: The Final Report and Recommendations of the Select Commission on Immigration and Refugee Policy With Supplemental Views by Commissioners 65-66 (1981); see § 4, 92 Stat. 907. Proposals to make unauthorized work a criminal offense were debated and discussed during the long process of drafting IRCA. See Brief for Service Employees International Union et al. as Amici Curiae 9-12. But Congress rejected them. See, e. g., 119 Cong. Rec. 14184 (1973) (statement of Rep. Dennis). In the end, IRCA’s framework reflects a considered judgment that making criminals out of aliens engaged in unauthorized work—aliens who already face the possibility of employer exploitation because of their removable status—would be inconsistent with federal policy and objectives. See, e. g., Hearings before Subcommittee No. 1 of the House Committee on the Judiciary, 92d Cong., 1st Sess., pt. 3, pp. 919-920 (1972) (statement of *406 Rep. Rodino, the eventual sponsor of IRCA in the House of Representatives).

IRCA’s express pre-emption provision, which in most instances bars States from imposing penalties on employers of unauthorized aliens, is silent about whether additional penalties may be imposed against the employees themselves. See 8 U.S.C. § 1324a(h)(2); Whiting, supra, at 587-588. But the existence of an “express pre-emption provisio[n] does not bar the ordinary working of conflict pre-emption principles” or impose a “ ‘special burden’ ” that would make it more difficult to establish the pre-emption of laws falling outside the clause. Geier v. American Honda Motor Co., 529 U. S. 861, 869-872 (2000); see Sprietsma v. Mercury Marine, 537 U. S. 51, 65 (2002).

The ordinary principles of pre-emption include the well-settled proposition that a state law is pre-empted where it “stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress.” Hines, 312 U. S., at 67. Under § 5(C) of S. B. 1070, Arizona law would interfere with the careful balance struck by Congress with respect to unauthorized employment of aliens. Although § 5(C) attempts to achieve one of the same goals as federal law—the deterrence of unlawful employment—it involves a conflict in the method of enforcement. The Court has recognized that a “[cjonflict in technique can be fully as disruptive to the system Congress erected as conflict in overt policy.” Motor Coach Employees v. Lockridge, 403 U. S. 274, 287 (1971). The correct instruction to draw from the text, structure, and history of IRCA is that Congress decided it would be inappropriate to impose criminal penalties on aliens who seek or engage in unauthorized employment. It follows that a state law to the contrary is an obstacle to the regulatory system Congress chose. See Puerto Rico Dept. of Consumer Affairs v. ISLA Petroleum Corp., 485 U. S. 495, 503 (1988) (“Where a comprehensive federal scheme intentionally leaves a portion of the regulated field without controls, then *407 the pre-emptive inference can be drawn—not from federal inaction alone, but from inaction joined with action”). Section 5(C) is pre-empted by federal law.

C

Section 6

Section 6 of S. B. 1070 provides that a state officer, “without a warrant, may arrest a person if the officer has probable cause to believe… [the person] has committed any public offense that makes [him] removable from the United States.” Ariz. Rev. Stat. Ann. § 13-3883(A)(5). The United States argues that arrests authorized by this statute would be an obstacle to the removal system Congress created.

As a general rule, it is not a crime for a removable alien to remain present in the United States. See INS v. Lopez-Mendoza, 468 U. S. 1032, 1038 (1984). If the police stop someone based on nothing more than possible removability, the usual predicate for an arrest is absent. When an alien is suspected of being removable, a federal official issues an administrative document called a “Notice to Appear.” See 8 U. S. C. § 1229(a); 8 CFR § 239.1(a). The form does not authorize an arrest. Instead, it gives the alien information about the proceedings, including the time and date of the removal hearing. See 8 U. S. C. § 1229(a)(1). If an alien fails to appear, an in absentia order may direct removal. § 1229a(b)(5)(A).

[A paragraph cataloguing the federal statutory structure for arrest during the removal process — §1226(a) warrants, Notices to Appear, 8 CFR §§241.2 and 242.2 — is omitted.]

*408 Section 6 attempts to provide state officers even greater authority to arrest aliens on the basis of possible removability than Congress has given to trained federal immigration officers. Under state law, officers who believe an alien is removable by reason of some “public offense” would have the power to conduct an arrest on that basis regardless of whether a federal warrant has issued or the alien is likely to escape. This state authority could be exercised without any input from the Federal Government about whether an arrest is warranted in a particular case. This would allow the State to achieve its own immigration policy. The result could be unnecessary harassment of some aliens (for instance, a veteran, college student, or someone assisting with a criminal investigation) who federal officials determine should not be removed.

This is not the system Congress created. Federal law specifies limited circumstances in which state officers may perform the functions of an immigration officer. A principal example is when the Attorney General has granted that authority to specific officers in a formal agreement with a state or local government. See § 1357(g)(1); see also § 1103(a)(10) (authority may be extended in the event of an “imminent mass influx of aliens arriving off the coast of the United *409 States”); § 1252c (authority to arrest in specific circumstance after consultation with the Federal Government); § 1324(c) (authority to arrest for bringing in and harboring certain aliens). Officers covered by these agreements are subject to the Attorney General’s direction and supervision. § 1357(g)(3). There are significant complexities involved in enforcing federal immigration law, including the determination whether a person is removable. See Padilla v. Kentucky, 559 U. S. 356, 379-380 (2010) (Alito, J., concurring in judgment). As a result, the agreements reached with the Attorney General must contain written certification that officers have received adequate training to carry out the duties of an immigration officer. See § 1357(g)(2); cf. 8 CFR §§ 287.5(c) (arrest power contingent on training), 287.1(g) (defining the training).

By authorizing state officers to decide whether an alien should be detained for being removable, § 6 violates the principle that the removal process is entrusted to the discretion of the Federal Government. See, e. g., Reno v. American-Arab Anti-Discrimination Comm., 525 U. S. 471, 483-484 (1999); see also Brief for Former INS Commissioners 8-13. A decision on removability requires a determination whether it is appropriate to allow a foreign national to continue living in the United States. Decisions of this nature touch on foreign relations and must be made with one voice. See Jama v. Immigration and Customs Enforcement, 543 U. S. 335, 348 (2005) (“Removal decisions, including the selection of a removed alien’s destination, may implicate [the Nation’s] relations with foreign powers and require consideration of changing political and economic circumstances” (internal quotation marks omitted)); see also Galvan v. Press, 347 U. S. 522, 531 (1954) (“Policies pertaining to the entry of aliens and their right to remain here are… entrusted exclusively to Congress… ”); Truax v. Raich, 239 U. S. 33, 42 (1915) (“The authority to control immigration—to *410 admit or exclude aliens—is vested solely in the Federal Government”).

In defense of § 6, Arizona notes a federal statute permitting state officers to “cooperate with the Attorney General in the identification, apprehension, detention, or removal of aliens not lawfully present in the United States.” 8 U. S. C. § 1357(g)(10)(B). There may be some ambiguity as to what constitutes cooperation under the federal law; but no coherent understanding of the term would incorporate the unilateral decision of state officers to arrest an alien for being removable absent any request, approval, or other instruction from the Federal Government. The Department of Homeland Security gives examples of what would constitute cooperation under federal law. These include situations where States participate in a joint task force with federal officers, provide operational support in executing a warrant, or allow federal immigration officials to gain access to detainees held in state facilities. See Dept. of Homeland Security, Guidance on State and Local Governments’ Assistance in Immigration Enforcement and Related Matters 13-14 (2011), online at http://www.dhs.gov/files/resources/immigration.shtm (all Internet materials as visited June 21, 2012, and available in Clerk of Court’s case file). State officials can also assist the Federal Government by responding to requests for information about when an alien will be released from their custody. See § 1357(d). But the unilateral state action to detain authorized by §6 goes far beyond these measures, defeating any need for real cooperation.

Congress has put in place a system in which state officers may not make warrantless arrests of aliens based on possible removability except in specific, limited circumstances. By nonetheless authorizing state and local officers to engage in these enforcement activities as a general matter, § 6 creates an obstacle to the full purposes and objectives of Congress. See Hines, 312 U. S., at 67. Section 6 is pre-empted by federal law.

*411 D

Section 2(B)

Section 2(B) of S. B. 1070 requires state officers to make a “reasonable attempt… to determine the immigration status” of any person they stop, detain, or arrest on some other legitimate basis if “reasonable suspicion exists that the person is an alien and is unlawfully present in the United States.” Ariz. Rev. Stat. Ann. § 11-1051(B). The law also provides that “[a]ny person who is arrested shall have the person’s immigration status determined before the person is released.” Ibid. The accepted way to perform these status checks is to contact ICE, which maintains a database of immigration records.

Three limits are built into the state provision. First, a detainee is presumed not to be an alien unlawfully present in the United States if he or she provides a valid Arizona driver’s license or similar identification. Second, officers “may not consider race, color or national origin… except to the extent permitted by the United States [and] Arizona Constitution^].” Ibid. Third, the provision must be “implemented in a manner consistent with federal laws regulating immigration, protecting the civil rights of all persons and respecting the privileges and immunities of United States citizens.” §11-1051(L).

The United States and its amici contend that, even with these limits, the State’s verification requirements pose an obstacle to the framework Congress put in place. The first concern is the mandatory nature of the status checks. The second is the possibility of prolonged detention while the checks are being performed.

1

Consultation between federal and state officials is an important feature of the immigration system. Congress has made clear that no formal agreement or special training needs to be in place for state officers to “communicate with *412 the [Federal Government] regarding the immigration status of any individual, including reporting knowledge that a particular alien is not lawfully present in the United States.” 8 U. S. C. § 1357(g)(10)(A). And Congress has obligated ICE to respond to any request made by state officials for verification of a person’s citizenship or immigration status. See § 1373(c); see also § 1226(d)(1)(A) (requiring a system for determining whether individuals arrested for aggravated felonies are aliens). ICE’s Law Enforcement Support Center operates “24 hours a day, seven days a week, 365 days a year” and provides, among other things, “immigration status, identity information and real-time assistance to local, state and federal law enforcement agencies.” ICE, Fact Sheet: Law Enforcement Support Center (May 29, 2012), online at http://www.iee.gov/news/library/factsheets/lesc.htm. LESC responded to more than 1 million requests for information in 2009 alone. App. 93.

The United States argues that making status verification mandatory interferes with the federal immigration scheme. It is true that §2(B) does not allow state officers to consider federal enforcement priorities in deciding whether to contact ICE about someone they have detained. See Brief for United States 47-50. In other words, the officers must make an inquiry even in cases where it seems unlikely that the Attorney General would have the alien removed. This might be the case, for example, when an alien is an elderly veteran with significant and longstanding ties to the community. See 2011 ICE Memorandum 4-5 (mentioning these factors as relevant).

Congress has done nothing to suggest it is inappropriate to communicate with ICE in these situations, however. Indeed, it has encouraged the sharing of information about possible immigration violations. See 8 U. S. C. § 1357(g) (10)(A). A federal statute regulating the public benefits provided to qualified aliens in fact instructs that “no State or local government entity may be prohibited, or in any way *413 restricted, from sending to or receiving from [ICE] information regarding the immigration status, lawful or unlawful, of an alien in the United States.” § 1644. The federal scheme thus leaves room for a policy requiring state officials to contact ICE as a routine matter. Cf. Whiting, 563 U. S., at 609-610 (rejecting argument that federal law pre-empted Arizona’s requirement that employers determine whether employees were eligible to work through the federal E-Verify system where the Federal Government had encouraged its use).

2

Some who support the challenge to §2(B) argue that, in practice, state officers will be required to delay the release of some detainees for no reason other than to verify their immigration status. See, e. g., Brief for Former Arizona Attorney General Terry Goddard et al. as Amici Curiae 37, n. 49. Detaining individuals solely to verify their immigration status would raise constitutional concerns. See, e. g., Arizona v. Johnson, 555 U. S. 323, 333 (2009); Illinois v. Caballes, 543 U. S. 405, 407 (2005) (“A seizure that is justified solely by the interest in issuing a warning ticket to the driver can become unlawful if it is prolonged beyond the time reasonably required to complete that mission”). And it would disrupt the federal framework to put state officers in the position of holding aliens in custody for possible unlawful presence without federal direction and supervision. Cf. Part IV-C, supra (concluding that Arizona may not authorize warrantless arrests on. the basis of removability). The program put in place by Congress does not allow state or local officers to adopt this enforcement mechanism.

But § 2(B) could be read to avoid these concerns. To take one example, a person might be stopped for jaywalking in Tucson and be unable to produce identification. The first sentence of §2(B) instructs officers to make a “reasonable” attempt to verify his immigration status with ICE if there is reasonable suspicion that his presence in the United States *414 is unlawful. The state courts may conclude that, unless the person continues to be suspected of some crime for which he may be detained by state officers, it would not be reasonable to prolong the stop for the immigration inquiry. See Reply Brief 12, n. 4 (“[Section 2(B)] does not require the verification be completed during the stop or detention if that is not reasonable or practicable”); cf. Muehler v. Mena, 544 U. S. 93, 101 (2005) (finding no Fourth Amendment violation where questioning about immigration status did not prolong a stop).

To take another example, a person might be held pending release on a charge of driving under the influence of alcohol. As this goes beyond a mere stop, the arrestee (unlike the jaywalker) would appear to be subject to the categorical requirement in the second sentence of § 2(B) that “[a]ny person who is arrested shall have the person’s immigration status determined before [he] is released.” State courts may read this as an instruction to initiate a status check every time someone is arrested, or in some subset of those cases, rather than as a command to hold the person until the check is complete no matter the circumstances. Even if the law is read as an instruction to complete a check while the person is in custody, moreover, it is not clear at this stage and on this record that the verification process would result in prolonged detention.

However the law is interpreted, if §2(B) only requires state officers to conduct a status check during the course of an authorized, lawful detention or after a detainee has been released, the provision likely would survive pre-emption—at least absent some showing that it has other consequences that are adverse to federal law and its objectives. There is no need in this case to address whether reasonable suspicion of illegal entry or another immigration crime would be a legitimate basis for prolonging a detention, or whether this too would be pre-empted by federal law. See, e. g., United States v. Di Re, 332 U. S. 581, 589 (1948) (authority of state officers to make arrests for federal crimes is, absent federal statutory instruction, a matter of state law); Gonzales v. Peo*415 ria, 722 F. 2d 468, 475-476 (CA9 1983) (concluding that Arizona officers have authority to enforce the criminal provisions of federal immigration law), overruled on other grounds in Hodgers-Durgin v. de la Vina, 199 F. 3d 1037 (CA9 1999).

The nature and timing of this case counsel caution in evaluating the validity of §2(B). The Federal Government has brought suit against a sovereign State to challenge the provision even before the law has gone into effect. There is a basic uncertainty about what the law means and how it will be enforced. At this stage, without the benefit of a definitive interpretation from the state courts, it would be inappropriate to assume §2(B) will be construed in a way that creates a conflict with federal law. Cf. Fox v. Washington, 236 U. S. 273, 277 (1915) (“So far as statutes fairly may be construed in such a way as to avoid doubtful constitutional questions they should be so construed; and it is to be presumed that state laws will be construed in that way by the state courts” (citation omitted)). As a result, the United States cannot prevail in its current challenge. See Huron Portland Cement Co. v. Detroit, 362 U. S. 440, 446 (1960) (“To hold otherwise would be to ignore the teaching of this Court’s decisions which enjoin seeking out conflicts between state and federal regulation where none clearly exists”). This opinion does not foreclose other pre-emption and constitutional challenges to the law as interpreted and applied after it goes into effect.

V

[A paragraph on a naturalization ceremony at the Smithsonian is omitted.]

*416 The National Government has significant power to regulate immigration. With power comes responsibility, and the sound exercise of national power over immigration depends on the Nation’s meeting its responsibility to base its laws on a political will informed by searching, thoughtful, rational civic discourse. Arizona may have understandable frustrations with the problems caused by illegal immigration while that process continues, but the State may not pursue policies that undermine federal law.

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The United States has established that §§3, 5(C), and 6 of S. B. 1070 are pre-empted. It was improper, however, to enjoin §2(B) before the state courts had an opportunity to construe it and without some showing that enforcement of the provision in fact conflicts with federal immigration law and its objectives.

The judgment of the Court of Appeals for the Ninth Circuit is affirmed in part and reversed in part. The case is remanded for further proceedings consistent with this opinion.

It is so ordered.

Justice Kagan took no part in the consideration or decision of this case.

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JUSTICE SCALIA, concurring in part and dissenting in part.

The United States is an indivisible “Union of sovereign States.” Hinderlider v. La Plata River & Cherry Creek Ditch Co., 304 U. S. 92, 104 (1938). Today’s opinion, *417 approving virtually all of the Ninth Circuit’s injunction against enforcement of the four challenged provisions of Arizona’s law, deprives States of what most would consider the defining characteristic of sovereignty: the power to exclude from the sovereign’s territory people who have no right to be there. Neither the Constitution itself nor even any law passed by Congress supports this result. I dissent.

I

As a sovereign, Arizona has the inherent power to exclude persons from its territory, subject only to those limitations expressed in the Constitution or constitutionally imposed by Congress. That power to exclude has long been recognized as inherent in sovereignty. Emer de Vattel’s seminal 1758 treatise on the Law of Nations stated:

“The sovereign may forbid the entrance of his territory either to foreigners in general, or in particular cases, or to certain persons, or for certain particular purposes, according as he may think it advantageous to the state. There is nothing in all this, that does not flow from the rights of domain and sovereignty: every one is obliged to pay respect to the prohibition; and whoever dares to violate it, incurs the penalty decreed to render it effectual.” The Law of Nations, bk. II, ch. VII, § 94, p. 309 (B. Kapossy & R. Whatmore eds. 2008).

[Omitted: the balance of Part I — Phillimore, the 1837 holding in Miln on the States’ pre-constitutional power, the Privileges and Immunities and Article I, §10 arguments, Neuman on the “lost century” of state immigration law, and the Alien and Sedition Acts controversy including the Kentucky and Virginia Resolutions.]

*420 In Mayor of New York v. Miln, this Court considered a New York statute that required the commander of any ship *421 arriving in New York from abroad to disclose “the name, place of birth, and last legal settlement, age and occupation… of all passengers… with the intention of proceeding to the said city.” 11 Pet., at 130-131. After discussing the sovereign authority to regulate the entrance of foreigners described by De Vattel, the Court said:

“The power… of New York to pass this law having undeniably existed at the formation of the constitution, the simple inquiry is, whether by that instrument it was taken from the states, and granted to congress; for if it were not, it yet remains with them.” Id., at 132.

And the Court held that it remains. Id., at 139.

[Omitted: the first three paragraphs of Part II — the Coolie Trade Act of 1862, the 1875 and 1882 immigration statutes, and Justice Scalia’s acceptance of federal immigration power as an inherent attribute of sovereignty rather than a naturalization power.]

II

*423 Possibility (1) need not be considered here: There is no federal law prohibiting the States’ sovereign power to exclude (assuming federal authority to enact such a law). The mere existence of federal action in the immigration area— and the so-called field pre-emption arising from that action, upon which the Court’s opinion so heavily relies, ante, at 401-403—cannot be regarded as such a prohibition. We are not talking here about a federal law prohibiting the States from regulating bubble-gum advertising, or even the construction of nuclear plants. We are talking about a federal law going to the core of state sovereignty: the power to exclude. Like elimination of the States’ other inherent sovereign power, immunity from suit, elimination of the States’ sovereign power to exclude requires that “Congress… unequivocally expres[s] its intent to abrogate,” Seminole Tribe of Fla. v. Florida, 517 U. S. 44, 55 (1996) (internal quotation marks omitted). Implicit “field pre-emption” will not do.

[Omitted: a paragraph rejecting the majority’s foreign-relations premise, including the passage on Medellín v. Texas.]

*424 What this case comes down to, then, is whether the Arizona law conflicts with federal immigration law—whether it excludes those whom federal law would admit, or admits those whom federal law would exclude. It does not purport to do so. It applies only to aliens who neither possess a privilege to be present under federal law nor have been removed pursuant to the Federal Government’s inherent authority. I proceed to consider the challenged provisions in detail.

§2(B)

“For any lawful stop, detention or arrest made by a law enforcement official… in the enforcement of any other law or ordinance of a county, city or town or this state where reasonable suspicion exists that the person is an alien and is unlawfully present in the United States, a reasonable attempt shall be made, when practicable, to determine the immigration status of the person, except if the determination may hinder or obstruct an investigation. Any person who is arrested shall have the person’s immigration status determined before the person is released…” S. B. 1070, § 2(B), as amended, Ariz. Rev. Stat. Ann. § 11-1051(B) (West 2012).

The Government has conceded that “even before Section 2 was enacted, state and local officers had state-law authority to inquire of DHS [the Department of Homeland Security] *425 about a suspect’s unlawful status and otherwise cooperate with federal immigration officers.” Brief for United States 47 (citing App. 62, 82); see also Brief for United States 48-49. That concession, in my view, obviates the need for further inquiry. The Government’s conflict-pre-emption claim calls on us “to determine whether, under the circumstances of this particular case, [the State’s] law stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress.” Hines v. Davidowitz, 312 U. S. 52, 67 (1941) (emphasis added). It is impossible to make such a finding without a factual record concerning the manner in which Arizona is implementing these provisions—something the Government’s preenforcement challenge has pretermitted. “The fact that [a law] might operate unconstitutionally under some conceivable set of circumstances is insufficient to render it wholly invalid, since we have not recognized an ‘overbreadth’ doctrine outside the limited context of the First Amendment.” United States v. Salerno, 481 U. S. 739, 745 (1987). And on its face, § 2(B) merely tells state officials that they are authorized to do something that they were, by the Government’s concession, already authorized to do.

The Court therefore properly rejects the Government’s challenge, recognizing that, “[a]t this stage, without the benefit of a definitive interpretation from the state courts, it would be inappropriate to assume § 2(B) will be construed in a way that creates a conflict with federal law.” Ante, at 415. Before reaching that conclusion, however, the Court goes to great length to assuage fears that “state officers will be required to delay the release of some detainees for no reason other than to verify their immigration status.” Ante, at 413. Of course, any investigatory detention, including one under §2(B), may become an “unreasonable… seizur[e],” U. S. Const., Amdt. 4, if it lasts too long. See Illinois v. Caballes, 543 U. S. 405, 407 (2005). But that has nothing to do with this case, in which the Government claims that § 2(B) is pre-empted by federal immigration law, not that anyone’s Fourth *426 Amendment rights have been violated. And I know of no reason why a protracted detention that does not violate the Fourth Amendment would contradict or conflict with any federal immigration law.

[Omitted: Justice Scalia’s discussion of §6, which covers ground Justice Alito covers at greater length below.]

*428 §3

“In addition to any violation of federal law, a person is guilty of willful failure to complete or carry an alien registration document if the person is in violation of 8 *429 [U.S.C.] § 1304(e) or 1306(a).” S. B. 1070, §3(A), as amended, Ariz. Rev. Stat. Ann. § 13-1509(A).

It is beyond question that a State may make violation of federal law a violation of state law as well. We have held that to be so even when the interest protected is a distinctively federal interest, such as protection of the dignity of the national flag, see Halter v. Nebraska, 205 U. S. 34 (1907), or protection of the Federal Government’s ability to recruit soldiers, Gilbert v. Minnesota, 254 U. S. 325 (1920). “[T]he State is not inhibited from making the national purposes its own purposes to the extent of exerting its police power to prevent its own citizens from obstructing the accomplishment of such purposes.” Id., at 331 (internal quotation marks omitted). Much more is that so when, as here, the State is protecting its own interest, the integrity of its borders. And we have said that explicitly with regard to illegal immigration: “Despite the exclusive federal control of this Nation’s borders, we cannot conclude that the States are without any power to deter the influx of persons entering the United States against federal law, and whose numbers might have a discernible impact on traditional state concerns.” Plyler v. Doe, 457 U. S. 202, 228, n. 23 (1982).

The Court’s opinion relies upon Hines v. Davidowitz, 312 U. S. 52. Ante, at 401. But that case did not, as the Court believes, establish a “field pre-emption” that implicitly eliminates the States’ sovereign power to exclude those whom federal law excludes. It held that the States are not permitted to establish “additional or auxiliary” registration requirements for aliens. 312 U. S., at 66-67. But § 3 does not establish additional or auxiliary registration requirements. It merely makes a violation of state law the very same failure to register and failure to carry evidence of registration that are violations of federal law. Hines does not prevent the State from relying on the federal registration system as “an available aid in the enforcement of a number of statutes of the state applicable to aliens whose constitutional validity *430 has not been questioned.” Id., at 75-76 (Stone, J., dissenting). One such statute is Arizona’s law forbidding illegal aliens to collect unemployment benefits, Ariz. Rev. Stat. Ann. § 23-781(B) (West 2012). To enforce that and other laws that validly turn on alien status, Arizona has, in Justice Stone’s words, an interest in knowing “the number and whereabouts of aliens within the state” and in having “a means of their identification,” 312 U. S., at 75. And it can punish the aliens’ failure to comply with the provisions of federal law that make that knowledge and identification possible.

*430 The Court points out, however, ante, at 402-403, that in some respects the state law exceeds the punishments prescribed by federal law: It rules out probation and pardon, which are available under federal law. The answer is that it makes no difference. Illegal immigrants who violate § 3 violate Arizona law. It is one thing to say that the Supremacy Clause prevents Arizona law from excluding those whom federal law admits. It is quite something else to say that a violation of Arizona law cannot be punished more severely than a violation of federal law. Especially where (as here) the State is defending its own sovereign interests, there is no precedent for such a limitation. The sale of illegal drugs, for example, ordinarily violates state law as well as federal *431 law, and no one thinks that the state penalties cannot exceed the federal. As I have discussed, moreover, “field preemption” cannot establish a prohibition of additional state penalties in the area of immigration.

*431 It holds no fear for me, as it does for the Court, that “[w]ere §3 to come into force, the State would have the power to bring criminal charges against individuals for violating a federal law even in circumstances where federal officials in charge of the comprehensive scheme determine that prosecution would frustrate federal policies.” Ante, at 402. That seems to me entirely appropriate when the State uses the federal law (as it must) as the criterion for the exercise of its own power, and the implementation of its own policies of excluding those who do not belong there. What I do fear—and what Arizona and the States that support it fear— is that “federal policies” of nonenforcement will leave the States helpless before those evil effects of illegal immigration that the Court’s opinion dutifully recites in its prologue {ante, at 397-398) but leaves unremedied in its disposition.

§5(C)

“It is unlawful for a person who is unlawfully present in the United States and who is an unauthorized alien to knowingly apply for work, solicit work in a public place or perform work as an employee or independent contractor in this state.” S. B. 1070, § 5(C), as amended, Ariz. Rev. Stat. Ann. § 13-2928(C) (West Supp. 2011).

Here, the Court rightly starts with De Canas v. Bica, 424 U. S. 351 (1976), which involved a California law providing that “ ‘[n]o employer shall knowingly employ an alien who is not entitled to lawful residence in the United States if *432 such employment would have an adverse effect on lawful resident workers.’” Id., at 352 (quoting Cal. Lab. Code Ann. § 2805(a)). This Court concluded that the California law was not pre-empted, as Congress had neither occupied the field of “regulation of employment of illegal aliens” nor expressed “the clear and manifest purpose” of displacing such state regulation. 424 U. S., at 356-357 (internal quotation marks omitted). Thus, at the time De Canas was decided, §5(C) would have been indubitably lawful.

The only relevant change is that Congress has since enacted its own restrictions on employers who hire illegal aliens, 8 U. S. C. § 1324a, in legislation that also includes some civil (but no criminal) penalties on illegal aliens who accept unlawful employment. The Court concludes from this (reasonably enough) “that Congress made a deliberate choice not to impose criminal penalties on aliens who seek, or engage in, unauthorized employment,” ante, at 405. But that is not the same as a deliberate choice to prohibit the States from imposing criminal penalties. Congress’s intent with regard to exclusion of state law need not be guessed at, but is found in the law’s express pre-emption provision, which excludes “any State or local law imposing civil or criminal sanctions (other than through licensing and similar laws) upon those who employ, or recruit or refer for a fee for employment, unauthorized aliens,” §1324a(h)(2) (emphasis added). Common sense, reflected in the canon expressio unius est exclusio alterius, suggests that the specification of pre-emption for laws punishing “those who employ” implies the lack of pre-emption for other laws, including laws punishing “those who seek or accept employment.”

The Court has no credible response to this. It quotes our jurisprudence to the effect that an “express pre-emption provisio[n] does not bar the ordinary working of conflict preemption principles.” Ante, at 406 (quoting Geier v. American Honda Motor Co., 529 U. S. 861, 869 (2000) (internal quotation marks omitted)). True enough—conflict pre-emption *433 principles. It then goes on to say that since “Congress decided it would be inappropriate to impose criminal penalties on aliens who seek or engage in unauthorized employment,” “[i]t follows that a state law to the contrary is an obstacle to the regulatory system Congress chose.” Ante, at 406. For “ ‘[wjhere a comprehensive federal scheme intentionally leaves a portion of the regulated field without controls, then the pre-emptive inference can be drawn.’” Ante, at 406-407 (quoting Puerto Rico Dept. of Consumer Affairs v. ISLA Petroleum Corp., 485 U. S. 495, 503 (1988)). All that is a classic description not of conflict pre-emption but of field pre-emption, which (concededly) does not occur beyond the terms of an express pre-emption provision.

The Court concludes that § 5(C) “would interfere with the careful balance struck by Congress,” ante, at 406 (another field pre-emption notion, by the way), but that is easy to say and impossible to demonstrate. The Court relies primarily on the fact that “[proposals to make unauthorized work a criminal offense were debated and discussed during the long process of drafting [the Immigration Reform and Control Act of 1986 (IRCA)],” “[b]ut Congress rejected them.” Ante, at 405. There is no more reason to believe that this rejection was expressive of a desire that there be no sanctions on employees, than expressive of a desire that such sanctions be left to the States. To tell the truth, it was most likely expressive of what inaction ordinarily expresses: nothing at all. It is a “naive assumption that the failure of a bill to make it out of committee, or to be adopted when reported to the floor, is the same as a congressional rejection of what the bill contained.” Crosby v. National Foreign Trade Council, 530 U. S. 363, 389 (2000) (Scalia, J., concurring in judgment) (internal quotation marks and brackets omitted).

[Omitted: the DACA passage. After argument and while the case was under submission, the Secretary of Homeland Security announced deferred action for some 1.4 million people; Justice Scalia sets out the criteria and writes that to say Arizona “contradicts federal law by enforcing applications of the Immigration Act that the President declines to enforce boggles the mind.” See the notes below.]

*435 The Court opinion’s looming specter of inutterable horror—“[i]f § 3 of the Arizona statute were valid, every State could give itself independent authority to prosecute federal registration violations,” ante, at 402—seems to me not so horrible and even less looming. But there has come to pass, and is with us today, the specter that Arizona and the States *436 that support it predicted: a Federal Government that does not want to enforce the immigration laws as written, and leaves the States’ borders unprotected against immigrants whom those laws would exclude. So the issue is a stark one. Are the sovereign States at the mercy of the Federal Executive’s refusal to enforce the Nation’s immigration laws?

A good way of answering that question is to ask: Would the States conceivably have entered into the Union if the Constitution itself contained the Court’s holding? Today’s judgment surely fails that test. At the Constitutional Convention of 1787, the delegates contended with “the jealousy of the states with regard to their sovereignty.” 1 Records of the Federal Convention 19 (M. Farrand ed. 1911) (statement of Edmund Randolph). Through ratification of the fundamental charter that the Convention produced, the States ceded much of their sovereignty to the Federal Government. But much of it remained jealously guarded—as reflected in the innumerable proposals that never left Independence Hall. Now, imagine a provision—perhaps inserted right after Art. I, § 8, cl. 4, the Naturalization Clause—which included among the enumerated powers of Congress “To establish Limitations upon Immigration that will be exclusive and that will be enforced only to the extent the President deems appropriate.” The delegates to the Grand Convention would have rushed to the exits.

As is often the case, discussion of the dry legalities that are the proper object of our attention suppresses the very human realities that gave rise to the suit. Arizona bears the brunt of the country’s illegal immigration problem. Its citizens feel themselves under siege by large numbers of illegal immigrants who invade their property, strain their social services, and even place their lives in jeopardy. Federal officials have been unable to remedy the problem, and indeed have recently shown that they are unwilling to do so. Thousands of Arizona’s estimated 400,000 illegal immigrants—including not just children but men and women under 30—are *437 now assured immunity from enforcement, and will be able to compete openly with Arizona citizens for employment.

Arizona has moved to protect its sovereignty—not in contradiction of federal law, but in complete compliance with it. The laws under challenge here do not extend or revise federal immigration restrictions, but merely enforce those restrictions more effectively. If securing its territory in this fashion is not within the power of Arizona, we should cease referring to it as a sovereign State. I dissent.

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JUSTICE THOMAS, concurring in part and dissenting in part.

I agree with Justice Scalia that federal immigration law does not pre-empt any of the challenged provisions of S. B. 1070. I reach that conclusion, however, for the simple reason that there is no conflict between the “ordinary meaning[]” of the relevant federal laws and that of the four provisions of Arizona law at issue here. Wyeth v. Levine, 555 U. S. 555, 588 (2009) (Thomas, J., concurring in judgment) (“Pre-emption analysis should not be a freewheeling judicial inquiry into whether a state statute is in tension with federal objectives, but an inquiry into whether the ordinary meanings of state and federal law conflict” (brackets and internal quotation marks omitted)).

Section 2(B) of S. B. 1070 provides that, when Arizona law enforcement officers reasonably suspect that a person they have lawfully stopped, detained, or arrested is unlawfully present, “a reasonable attempt shall be made, when practicable, to determine the immigration status of the person” pursuant to the verification procedure established by Congress in 8 U.S.C. § 1373(c). Ariz. Rev. Stat. Ann. § 11-1051(B) (West 2012). Nothing in the text of that or any other federal statute prohibits Arizona from directing its officers to make immigration-related inquiries in these situations. To the contrary, federal law expressly states that “no State or local government entity may be prohibited, or in any way *438 restricted, from sending to or receiving from” federal officials “information regarding the immigration status” of an alien. 8 U. S. C. § 1644. And, federal law imposes an affirmative obligation on federal officials to respond to a State’s immigration-related inquiries. § 1373(c).

Section 6 of S. B. 1070 authorizes Arizona law enforcement officers to make warrantless arrests when there is probable cause to believe that an arrestee has committed a public offense that renders him removable under federal immigration law. States, as sovereigns, have inherent authority to conduct arrests for violations of federal law, unless and until Congress removes that authority. See United States v. Di Re, 332 U. S. 581, 589 (1948) (holding that state law determines the validity of a warrantless arrest for a violation of federal law “in [the] absence of an applicable federal statute”). Here, no federal statute purports to withdraw that authority. As Justice Scalia notes, ante, at 426 (opinion concurring in part and dissenting in part), federal law does limit the authority of federal officials to arrest removable aliens, but those statutes do not apply to state officers. And, federal law expressly recognizes that state officers may “cooperate with the Attorney General” in the “apprehension” and “detention” of “aliens not lawfully present in the United States.” § 1357(g)(10)(B). Nothing in that statute indicates that such cooperation requires a prior “request, approval, or other instruction from the Federal Government.” Ante, at 410 (majority opinion).

Section 3 of S. B. 1070 makes it a crime under Arizona law for an unlawfully present alien to willfully fail to complete or carry an alien registration document in violation of 8 U. S. C. §§ 1304(e) and 1306(a). Section 3 simply incorporates federal registration standards. Unlike the Court, I would not hold that Congress pre-empted the field of enforcing those standards. “[O]ur recent cases have frequently rejected field pre-emption in the absence of statutory language expressly requiring it.” Camps Newfound/Owatonna, Inc. *439 v. Town of Harrison, 520 U. S. 564, 617 (1997) (Thomas, J., dissenting); see, e. g., New York State Dept. of Social Servs. v. Dublino, 413 U. S. 405, 415 (1973). Here, nothing in the text of the relevant federal statutes indicates that Congress intended enforcement of its registration requirements to be exclusively the province of the Federal Government. That Congress created a “full set of standards governing alien registration,” ante, at 401 (majority opinion), merely indicates that it intended the scheme to be capable of working on its own, not that it wanted to preclude the States from enforcing the federal standards. Hines v. Davidowitz, 312 U. S. 52 (1941), is not to the contrary. As Justice Scalia explains, ante, at 429, Hines at most holds that federal law pre-empts the States from creating additional registration requirements. But here, Arizona is merely seeking to enforce the very registration requirements that Congress created.

Section 5(C) of S. B. 1070 prohibits unlawfully present aliens from knowingly applying for, soliciting, or performing work in Arizona. Section 5(C) operates only on individuals whom Congress has already declared ineligible to work in the United States. Nothing in the text of the federal immigration laws prohibits States from imposing their own criminal penalties on such individuals. Federal law expressly pre-empts States from “imposing civil or criminal sanctions (other than through licensing and similar laws) upon those who employ, or recruit or refer for a fee for employment, unauthorized aliens.” 8 U. S. C. § 1324a(h)(2) (emphasis added). But it leaves States free to impose criminal sanctions on the employees themselves.

Despite the lack of any conflict between the ordinary meaning of the Arizona law and that of the federal laws at issue here, the Court holds that various provisions of the Arizona law are pre-empted because they “stan[d] as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress.” Hines, supra, at 67. *440 I have explained that the “purposes and objectives” theory of implied pre-emption is inconsistent with the Constitution because it invites courts to engage in freewheeling speculation about congressional purpose that roams well beyond statutory text. See Wyeth, 555 U. S., at 604 (opinion concurring in judgment); see also Williamson v. Mazda Motor of America, Inc., 562 U. S. 323, 340-341 (2011) (opinion concurring in judgment); Haywood v. Drown, 556 U. S. 729, 767 (2009) (dissenting opinion). Under the Supremacy Clause, pre-emptive effect is to be given to congressionally enacted laws, not to judicially divined legislative purposes. See Wyeth, supra, at 604 (Thomas, J., concurring in judgment). Thus, even assuming the existence of some tension between Arizona’s law and the supposed “purposes and objectives” of Congress, I would not hold that any of the provisions of the Arizona law at issue here are pre-empted on that basis.

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JUSTICE ALITO, concurring in part and dissenting in part.

This case concerns four provisions of Arizona’s Support Our Law Enforcement and Safe Neighborhoods Act, S. B. 1070. Section 2(B) requires Arizona law enforcement officers to make a “reasonable attempt,” “when practicable,” to ascertain the immigration status of any person who an officer lawfully stops, detains, or arrests “where reasonable suspicion exists that the person is an alien and is unlawfully present in the United States.” Ariz. Rev. Stat. Ann. §11-1051(B) (West 2012). Section 3 provides that an alien who willfully fails “to complete or carry an alien registration document” in violation of 8 U. S. C. § 1304(e) or § 1306(a) is guilty of a misdemeanor. Ariz. Rev. Stat. Ann. § 13-1509(A) (West Supp. 2011). Section 5(C) makes it a misdemeanor for an unauthorized alien who is unlawfully present in the United States “to knowingly apply for work, solicit work in a public place or perform work as an employee or independent contractor.” Ariz. Rev. Stat. Ann. §13-2928(C). And §6 *441 authorizes Arizona law enforcement officers to arrest without a warrant any person who an officer has probable cause to believe “has committed any public offense that makes the person removable from the United States.” Ariz. Rev. Stat. Ann. § 13-3883(A)(5).

I agree with the Court that § 2(B) is not pre-empted. That provision does not authorize or require Arizona law enforcement officers to do anything they are not already allowed to do under existing federal law. The United States’ argument that § 2(B) is pre-empted, not by any federal statute or regulation, but simply by the Executive’s current enforcement policy is an astounding assertion of federal executive power that the Court rightly rejects.

I also agree with the Court that § 3 is pre-empted by virtue of our decision in Hines v. Davidowitz, 312 U. S. 52 (1941). Our conclusion in that case that Congress had enacted an “all-embracing system” of alien registration and that States cannot “enforce additional or auxiliary regulations,” id., at 66-67, 74, forecloses Arizona’s attempt here to impose additional, state-law penalties for violations of the federal registration scheme.

While I agree with the Court on §§2(B) and 3,1 part ways on § § 5(C) and 6. The Court’s holding on §5(C) is inconsistent with De Canas v. Bica, 424 U. S. 351 (1976), which held that employment regulation, even of aliens unlawfully present in the country, is an area of traditional state concern. Because state police powers are implicated here, our precedents require us to presume that federal law does not displace state law unless Congress’ intent to do so is clear and manifest. I do not believe Congress has spoken with the requisite clarity to justify invalidation of §5(C). Nor do I believe that §6 is invalid. Like §2(B), §6 adds virtually nothing to the authority that Arizona law enforcement officers already exercise. And whatever little authority they have gained is consistent with federal law.

*442 Section 2(B)

A

[Omitted from Part A: the detailed account of §1357(g)(10)(A), §1373(a) and (c), and §1644, and the survey of state and local practice; and the paragraphs answering the United States’ “mandatory verification” argument.]

Although §2(B) of the Arizona law has occasioned much controversy, it adds nothing to the authority that Arizona law enforcement officers, like officers in all other States, already possess under federal law. For that reason, I agree with the Court that § 2(B) is not pre-empted.

*445 The United States’ attack on § 2(B) is quite remarkable. The United States suggests that a state law may be pre-empted, not because it conflicts with a federal statute or regulation, but because it is inconsistent with a federal agency’s current enforcement priorities. Those priorities, however, are not law. They are nothing more than agency policy. I am aware of no decision of this Court recognizing that mere policy can have pre-emptive force. Cf. Barclays Bank PLC v. Franchise Tax Bd. of Cal., 512 U. S. 298, 380 (1994) (holding that “Executive Branch communications that express federal policy but lack the force of law cannot render unconstitutional” an “otherwise valid, congressionally condoned” state law). If § 2(B) were pre-empted at the present time because it is out of sync with the Federal Government’s current priorities, would it be unpre-empted at some time in the future if the agency’s priorities changed?

*446 B

[Omitted from Part B: the traffic-stop hypothetical and the Fourth Amendment analysis that follows it — Di Re, Miller, Caballes, Muehler v. Mena and Hayes v. Florida.]

*449 If properly implemented, § 2(B) should not lead to federal constitutional violations, but there is no denying that enforcement of § 2(B) will multiply the occasions on which sensitive Fourth Amendment issues will crop up. These civil-liberty concerns, I take it, are at the heart of most objections to § 2(B). Close and difficult questions will inevitably arise as to whether an officer had reasonable suspicion to believe that a person who is stopped for some other reason entered the country illegally, and there is a risk that citizens, lawful permanent residents, and others who are lawfully present in the country will be detained. To mitigate this risk, Arizona could issue guidance to officers detailing the circumstances that typically give rise to reasonable suspicion of unlawful presence. And in the spirit of the federal-state cooperation that the United States champions, the Federal Government could share its own guidelines. Arizona could also provide officers with a nonexclusive list containing forms of identification sufficient under § 2(B) to dispel any suspicion of unlawful presence. If Arizona accepts licenses from most States as proof of legal status, the problem of roadside detentions will be greatly mitigated.

[Footnote 1: When the REAL ID Act of 2005 takes effect, the Federal Government will no longer accept state forms of identification that fail to meet certain federal requirements. § 202(a)(1), 119 Stat. 312. One requirement is that any identification be issued only on proof that the applicant is lawfully *450 present in the United States. § 202(c)(2)(B), id., at 313. I anticipate that most, if not all, States will eventually issue forms of identification that suffice to establish lawful presence under § 2(B).]

*450 Section 3

I agree that §3 is pre-empted because, like the Court, I read the opinion in Hines to require that result. Although there is some ambiguity in Hines, the Court largely spoke in the language of field pre-emption. The Court explained that where Congress “has enacted a complete scheme of regulation and has therein provided a standard for the registration of aliens, states cannot, inconsistently with the purpose of Congress, conflict or interfere with, curtail or complement, the federal law, or enforce additional or auxiliary regulations.” 312 U. S., at 66-67. In finding the Pennsylvania alien-registration law pre-empted, the Court observed that Congress had “provided a standard for alien registration in a single integrated and all-embracing system” and that its intent was “to protect the personal liberties of law-abiding aliens through one uniform national registration system.” Id., at 74. If we credit our holding in Hines that Congress has enacted “a single integrated and all-embracing system” of alien registration and that States cannot “complement” that system or “enforce additional or auxiliary regulations,” id., at 66-67, 74, then Arizona’s attempt to impose additional, state-law penalties for violations of federal registration requirements must be invalidated.

Section 5(C)

While I agree that § 3 is pre-empted, I disagree with the Court’s decision to strike down § 5(C). I do so in large measure because the Court fails to give the same solicitude to our decision in De Canas, 424 U. S. 351, as it is willing to give our decision in Hines. In De Canas, the Court upheld against a pre-emption challenge a state law imposing fines on employers that hired aliens who were unlawfully present in the *451 United States. The Court explained that the mere fact that “aliens are the subject of a state statute does not render it a regulation of immigration.” 424 U. S., at 355. The Court emphasized instead that “States possess broad authority under their police powers to regulate the employment relationship to protect workers within the State.” Id., at 356. In light of that broad authority, the Court declared that “[o]nly a demonstration that complete ouster of state power… was The clear and manifest purpose of Congress’ would justify” the conclusion that “state regulation designed to protect vital state interests must give way to paramount federal legislation.” Id., at 357 (some internal quotation marks omitted); see also Bates v. Dow Agrosciences LLC, 544 U. S. 431, 449 (2005) (“In areas of traditional state regulation, [the Court] assume[s] that a federal statute has not supplanted state law unless Congress has made such an intention ‘clear and manifest’” (some internal quotation marks omitted)).

[Omitted: a paragraph noting that federal regulation in this area is more pervasive today than when De Canas was decided.]

*451 The Court gives short shrift to our presumption against pre-emption. Having no express statement of congressional intent to support its analysis, the Court infers from stale legislative history and from the comprehensiveness of the federal scheme that “Congress made a deliberate choice not to impose criminal penalties on aliens who seek, or engage in, unauthorized employment.” Ante, at 405. Because §5(C) imposes such penalties, the Court concludes that it stands *452 as an obstacle to the method of enforcement chosen by Congress. Ante, at 406-407.

The one thing that is clear from the federal scheme is that Congress chose not to impose federal criminal penalties on aliens who seek or obtain unauthorized work. But that does not mean that Congress also chose to pre-empt state criminal penalties. The inference is plausible, but far from necessary. As we have said before, the “decision not to adopt a regulation” is not “the functional equivalent of a regulation prohibiting all States and their political subdivisions from adopting such a regulation.” Sprietsma v. Mercury Marine, 537 U. S. 51, 65 (2002). With any statutory scheme, Congress chooses to do some things and not others. If that alone were enough to demonstrate pre-emptive intent, there would be little left over for the States to regulate, especially now that federal authority reaches so far and wide. States would occupy tiny islands in a sea of federal power. This explains why state laws implicating traditional state powers are not pre-empted unless there is a “clear and manifest” congressional intention to do so.

Not only is there little evidence that Congress intended to pre-empt state laws like § 5(C), there is some evidence that Congress intended the opposite result. In making it unlawful for employers to hire unauthorized aliens, see 8 U. S. C. § 1324a(a), Congress made it clear that “any State or local law imposing civil or criminal sanctions (other than through licensing and similar laws)” upon employers was pre-empted, § 1324a(h)(2). Noticeably absent is any similar directive pre-empting state or local laws targeting aliens who seek or obtain unauthorized employment. Given that Congress expressly pre-empted certain state and local laws pertaining to employers but remained silent about laws pertaining to employees, one could infer that Congress intended to preserve state and local authority to regulate the employee side of the equation. At the very least, it raises serious *453 doubts about whether Congress intended to pre-empt such authority.

The Court dismisses any inferences that might be drawn from the express pre-emption provision. See ante, at 406. But even though the existence of that provision “does not bar the ordinary working of conflict pre-emption principles” or impose a “ ‘special burden’ ” against pre-emption, Geier v. American Honda Motor Co., 529 U. S. 861, 869-870 (2000), it is still probative of congressional intent. And it is the intent of Congress that is the “ultimate touchstone.” Retail Clerks v. Schermerhorn, 375 U. S. 96, 103 (1963).

The Court infers from Congress’ decision not to impose federal criminal penalties that Congress intended to preempt state criminal penalties. But given that the express pre-emption provision covers only state and local laws regulating employers, one could just as well infer that Congress did not intend to pre-empt state or local laws aimed at alien employees who unlawfully seek or obtain work. Surely Congress’ decision not to extend its express pre-emption provision to state or local laws like § 5(C) is more probative of its intent on the subject of pre-emption than its decision not to impose federal criminal penalties for unauthorized work. In any event, the point I wish to emphasize is that inferences can be drawn either way. There are no necessary inferences that point decisively for or against pre-emption. Therefore, if we take seriously that state employment regulation is a traditional state concern and can be pre-empted only on a showing of “clear and manifest” congressional intent as required by De Canas, then § 5(C) must survive. “Our precedents establish that a high threshold must be met if a state law is to be pre-empted for conflicting with the purposes of a federal Act.” Chamber of Commerce of United States of America v. Whiting, 563 U. S. 582, 607 (2011) (plurality opinion) (internal quotation marks omitted). I do not believe the United States has surmounted that barrier here.

*454 Section 6

I also disagree with the Court’s decision that §6 is pre-empted. This provision adds little to the authority that Arizona officers already possess, and whatever additional authority it confers is consistent with federal law. Section 6 amended an Arizona statute that authorizes warrantless arrests. See Ariz. Rev. Stat. Ann. §13-3883 (West 2010). Before § 6 was added, that statute already permitted arrests without a warrant for felonies, misdemeanors committed in the arresting officer’s presence, petty offenses, and certain traffic-related criminal violations. See §§ 13-3883(A)(l)-(4). Largely duplicating the authority already conferred by these prior subsections, §6 added a new subsection, §13-3883(A)(5) (West Supp. 2011), that authorizes officers to make warrantless arrests on probable cause that the arrestee has committed a “public offense” for which the arrestee is removable from the United States. A “public offense” is defined as conduct that is punishable by imprisonment or a fine according to the law of the State where the conduct occurred and that would be punishable under Arizona law had the conduct occurred in Arizona. See § 13-105(27).

[Omitted: the remainder of Part A on §6 — the three narrow categories in which §6 enlarges arrest authority, Di Re and Miller, and §1357(g)(10)(B).]

*456 To be sure, were an officer to persist in making an arrest that the officer knows is unwanted, such conduct would not count as cooperation. But nothing in the relevant federal statutes suggests that Congress does not want aliens who have committed removable offenses to be arrested. To the contrary, § 1226(c)(1) commands that the Executive “shall take into custody any alien” who is deportable for having committed a specified offense. And § 1226(c)(2) substantially limits the circumstances under which the Executive has discretion to release aliens held in custody under paragraph (1). So if an officer arrests an alien who is removable for having committed one of the crimes listed in § 1226(c)(1), the Federal Government is obligated to take the alien into custody.

[Footnote 2: That goes for the Executive Branch as well, which has made the apprehension and removal of criminal aliens a priority. See App. 108.]

[Omitted: the §1226(c)(1) and §1226(a) analysis.]

*457 It bears emphasizing that §6 does not mandate the warrantless apprehension of all aliens who have committed crimes for which they are removable. Instead, it only grants state and local officers permission to make such arrests. The trouble with this premature, facial challenge is that it affords Arizona no opportunity to implement its law in a way that would avoid any potential conflicts with federal law. For example, Arizona could promulgate guidelines or regulations limiting the arrest authority conferred by § 6 to *458 the crimes specified in § 1226(c)(1). And to the extent § 1226(c)(1) is unclear about which exact crimes are covered, Arizona could go even further and identify specific crimes for which there is no doubt an alien would be removable. The point is that there are plenty of permissible applications of § 6, and the Court should not invalidate the statute at this point without at least some indication that Arizona has implemented it in a manner at odds with Congress’ clear and manifest intent. We have said that a facial challenge to a statute is “the most difficult challenge to mount successfully” because “the challenger must establish that no set of circumstances exists under which the [statute] would be valid.” United States v. Salerno, 481 U. S. 739, 745 (1987); see also Anderson v. Edwards, 514 U. S. 143, 155, n. 6 (1995) (applying the Salerno standard in a pre-emption case). As to § 6, I do not believe the United States has carried that heavy burden.

[Footnote 3: I readily admit that it can be difficult to determine whether a particular conviction will necessarily make an alien removable. See Padilla v. Kentucky, 559 U. S. 356, 377-378 (2010) (Alito, J., concurring in judgment).]

[Omitted: Part B, on whether §6 gives state officers greater arrest authority than §1357(a)(2) gives federal officers.]

Notes & Questions

1. Three doctrines, one statute. Section 3 is preempted because Congress occupied the field; §§5(C) and 6 are preempted because they obstruct congressional objectives; §2(B) is not adjudicated at all. Work out what each holding would require a state legislature to change. Could Arizona have saved §3 by writing a different penalty? (At 402–403 the Court says the probation and pardon differences “underscore the reason for field pre-emption” — which tells you the answer is no, and tells you why field preemption is the strongest of the three.) Could it have saved §5(C)? §6?

2. The same sentence, two jobs. Hines at 67 supplies the obstacle test the Court uses to strike §5(C) and §6. Hines at 66–67 and 74 supplies the field holding the Court uses to strike §3. One 1941 opinion, two doctrines, both operating in a single case sixty-one years later. Go back to the Hines note in this module and ask whether that opinion can carry both loads — remembering that Justice Black said in terms that no “rigid formula or rule” could be used as a universal pattern.

3. Hines four ways, and what that shows. Kennedy (401, 403), Scalia (429), Thomas (439) and Alito (450) all cite 312 U. S. at 66–67 and 74. Kennedy gets field preemption. Scalia gets a narrow holding about “additional or auxiliary” requirements, read through Justice Stone’s dissent. Thomas gets “at most” a bar on additional registration requirements. Alito gets field preemption, concedes it reluctantly, and applies it to nothing else. Is this a failure of the opinion, of the doctrine, or of precedent as a method? Note the cost of the disagreement: it decides whether a state criminal statute stands.

4. What “upheld” means. Students and headlines will tell you the Court upheld §2(B). Read 414–416 again. The Court says the challenge is premature, that §2(B) “likely would survive” on one reading, that it will not assume a conflicting construction “at this stage,” and that its opinion “does not foreclose other pre-emption and constitutional challenges.” Then notice what is not in the opinion: the phrase “not pre-empted” never appears in the opinion of the Court, the Fourth Amendment appears once and only inside a citation parenthetical, and Salerno and the word “facial” appear nowhere in the majority. What is the precedential holding of Part IV-D? And what would a plaintiff have to show, and when, to bring the challenge the Court invites?

5. Race is not in this case. The words “Hispanic,” “race,” “discriminat-” and “profiling” appear a combined handful of times, every one of them spurious — a publisher’s name, a quotation of §2(B)‘s own no-consideration-of-race clause at 411, and a case name. The phrase “show me your papers” does not appear. The closest anyone comes is Justice Alito at 449: enforcement “will multiply the occasions on which sensitive Fourth Amendment issues will crop up,” and “[t]hese civil-liberty concerns, I take it, are at the heart of most objections to §2(B).” The dissenting-in-part Justice is the only one who names what the public fight was about. Ask what it means that a constitutional decision about a statute everyone understood as an immigration-enforcement measure was litigated and decided entirely as a question of statutory conflict.

6. Justice Thomas’s straight line. In Wyeth he supplied the sixth vote for Levine while calling obstacle preemption unconstitutional. Here he would uphold all four Arizona provisions and repeats the objection verbatim, citing Wyeth at 588 and twice at 604. In Monsanto v. Durnell he joins an express-preemption majority in full and writes separately to ask whether agency action can preempt at all. Three cases, one position, three different results for the party invoking federal law. Is that a principled method or a set of preferences that happens to be stated in constitutional terms? Make the strongest case each way.

7. Justice Scalia and the clear-statement rule. At 423 he argues that eliminating a State’s sovereign power to exclude requires that “Congress … unequivocally expres[s] its intent to abrogate,” on the analogy of sovereign immunity, and concludes: “Implicit ‘field pre-emption’ will not do.” Compare Justice Kennedy’s Gade concurrence, which asked for a conflict that is “irreconcilable” and an objective “conveyed with clarity in the federal legislation.” Are these the same proposal? If a clear-statement rule for preemption were adopted, which cases in this module come out differently — Rice? PG&E? Crosby? Wyeth?

8. The DACA passage, omitted above. After argument and while the case was under submission, the Secretary of Homeland Security announced deferred action for roughly 1.4 million people. Justice Scalia sets out the criteria from a news report and a DHS memorandum and writes that to say Arizona “contradicts federal law by enforcing applications of the Immigration Act that the President declines to enforce boggles the mind.” Two questions, and keep them separate. First, the propriety: is it appropriate for a Justice to rest an opinion on an executive action announced after argument, on which no party was heard? Second, the merits: if federal preemptive force comes from “the full purposes and objectives of Congress,” does an executive decision not to enforce change those objectives — and if it does not, what is the preempting federal law in a §6 case?

9. Where this sits in the module. Arizona is the module’s synthesis case: it names all three implied categories in one doctrinal recital at 399–400, applies two of them in the same opinion, declines the third, and generates a separate opinion arguing that each of the three was misapplied. Set it beside Monsanto v. Durnell, which decides a major preemption case without reaching implied preemption at all. Between 2012 and 2026, has the Court’s center of gravity moved from implied preemption toward express preemption — and if so, is that a retreat from “freewheeling judicial inquiry” or simply a relocation of the same discretion into the reading of words like “under”?