The Supreme Court issued its decision in Arizona v. United States today, which dealt with the federal government’s challenge to Arizona’s controversial immigration law, S.B. 1070, which gave local law enforcement enhanced rights to police the immigration status of individuals and essentially forced immigrants to carry papers with them showing that they are legally in the country. The court issued a decision that struck down portions of the law while allowing others to remain in effect. The court held that federal law does not preempt Arizona’s instruction to law enforcement to check the immigration status of people they detain. It is important to note, however, that this ruling does leave open the possibility that this particular provision could be reviewed and ultimately struck down if its enforcement is allegedly being done in a discriminatory fashion.

The question before the Court is whether federal law preempts and renders invalid four separate provisions of the state law. … The issue is whether, under pre­emption principles, federal law permits Arizona to imple­ment the state-law provisions in dispute. … 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 section 1304(e) or 1306(a).”  Ariz. Rev. Stat. Ann. §11–1509(A) (West Supp. 2011). … 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 enforc[ing] additional or auxiliary regulations.”  312 U. S., at 66–67. Section 3 is preempted by federal law.  … §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) (West Supp. 2011). … Section 5(C) is preempted by federal law. [IRCA.] … 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) (West Supp. 2011). … 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 preempted by federal law. … 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) (West 2012). … 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.  …  As a result, the United States cannot prevail in its current challenge. … This opinion does not foreclose other preemption and constitutional challenges to the law as interpreted and applied after it goes into effect.” – Arizona v. U.S., June 25, 2012.