Arizona v. United States

LII note: The U.S. Supreme Court has now decided Arizona v. United States.


Can Arizona engage in cooperative enforcement of federal immigration laws and create state offenses for violations of federal immigration regulations?

Oral argument: 
April 25, 2012

In 2010, Arizona enacted the Support Our Law Enforcement and Safe Neighborhoods Act, which creates state immigration offenses and expands local police officers’ immigration law enforcement authority. The United States sued Arizona in federal district court, arguing the state law was preempted by federal law, and sought a preliminary injunction to prevent the state law from taking effect. The district court granted a preliminary injunction with respect to four provisions of the Arizona law and the Ninth Circuit affirmed. Petitioners, the State of Arizona and the Governor of Arizona, Janice K. Brewer, argue that federal law does not preempt its statute because Arizona’s statute merely creates a formal cooperative relationship between federal and state officers to implement federal laws. Respondent, the United States, asserts that implementation of the statute would infringe upon the Executive Branch’s exclusive authority to regulate immigration, and is therefore invalid.

Questions as Framed for the Court by the Parties 

Arizona enacted the Support Our Law Enforcement and Safe Neighborhoods Act (S.B. 1070) to address the illegal immigration crisis in the State. The four provisions of S.B. 1070 enjoined by the courts below authorize and direct state law-enforcement officers to cooperate and communicate with federal officials regarding the enforcement of federal immigration law and impose penalties under state law for non-compliance with federal immigration requirements.

The question presented is whether the federal immigration laws preclude Arizona's efforts at cooperative law enforcement and impliedly preempt these four provisions of S.B. 1070 on their face.


The state of Arizona maintains that it faced rampant illegal immigration, which increased crime and harmed Arizona’s economy. In response to this concern, in April 2010, the Arizona State Legislature enacted the Support Our Law Enforcement and Safe Neighborhoods Act (“S.B. 1070”), which establishes or amends state immigration offenses and defines local police officers’ immigration law enforcement authority. Section 1 of S.B. 1070 states that the Arizona legislature’s goal in enacting this statute was to deter illegal immigrants from entering the country and from engaging in economic activity.

S.B. 1070 attempts to accomplish that purpose through a number of provisions. UnderSection 2, when an officer, performing a lawful stop or arrest, reasonably believes that a person is in the United States illegally, the officer must determine that person’s immigration status. Section 2(B) requires that officers check an arrested person’s immigration status before releasing that person. Section 3 creates a state criminal offense for failing to carry immigration documents, but it prohibits officers from using race or national origin when enforcing the provision. Under Section 4 of S.B. 1070, an officer charged with enforcing human trafficking laws has authority to stop a driver when the officer reasonably believes that the person committed any civil traffic violation. Section 5 prohibits motor vehicle drivers from blocking traffic while attempting to employ a person for work at a different location—Section 5(C) likewise prohibits an unlawful alien from performing, soliciting, or applying for work. Section 6 authorizes a warrantless arrest when an officer has probable cause to believe that a person has committed an offense for which the person could be removed from the United States. The Arizona law also amends current sanctions to deter employers from hiring illegal aliens (Sections 7, 8, and 9) and authorizes an officer to impound a vehicle used to transport unlawful aliens (Section 10).

The United States challenged S.B. 1070 in the United States District Court for the District of Arizona, alleging that the statute violated the Commerce Clause and was preempted by the federal statutory framework established largely through the Immigration and Nationality Act (“INA”). The United States sought a preliminary injunction to prevent the Arizona law from taking effect until questions concerning constitutionality could be resolved. Bringing challenges to S.B. 1070’s first six provisions, the United States sought an injunction to prevent the law’s implementation in its entirety. The district court granted the preliminary injunction with respect to Sections 2(B), 3, 5(C), and 6, and the Ninth Circuit affirmed. Arizona appealed, and the Supreme Court granted certiorari on December 12, 2011.


The issue before the Supreme Court is whether federal immigration laws preempt Arizona’s Support Our Law Enforcement and Safe Neighborhoods Act (“S.B. 1070”), the provisions of which order state law enforcement officers to work with federal officers in enforcing federal immigration laws and institute state penalties for any failure to comply with federal immigration laws. The Ninth Circuit affirmed the district court’s issuance of a preliminary injunction to prevent Arizona from enforcing four key provisions of S.B. 1070. A preliminary injunction is granted if the plaintiff can prove that it is likely to succeed on the merits of the underlying claim, that the plaintiff will suffer irreparable harm if the injunction is not granted, and that the balance of equities and the public interest are in favor of granting the injunction. Here, the Ninth Circuit found that the United States was likely to succeed on the merits of its claim that federal law preempted S.B. 1070 and affirmed the injunction.

Petitioners State of Arizona and Janice K. Brewer, in her official capacity as Governor of Arizona, argue that since S.B. 1070 simply seeks to enforce federal law in cooperation with federal officers rather than enforce Arizona’s own state standards, federal law cannot preempt the statute. However, the United States contends that the federal government holds exclusive power to regulate immigration, that immigration is closely related to foreign affairs, and that Arizona cannot adopt its own immigration policies because it frustrates objectives.

Infringement upon Federal Government’s Discretionary Right to Set Immigration Policies

The United States argues that the power to regulate immigration is exclusively federal. The United States maintains that exclusively federal regulation of immigration is necessary because nation’s relations with aliens residing in its territory are intertwined with the United States’ relationships with other nations, and that it is crucial that the country presents a single policy on immigration. The United States contends that the Immigration and Nationality Act (“INA”), which thoroughly regulates the status of aliens, gave the Executive Branch the ability to exercise its full discretion. The United States cites the Executive Branch’s ability to abandon removal proceedings without its decisions being subject to judicial review, its ability to free aliens on bond or conditional parole, and its ability to grant aliens relief from removal as examples of its discretion. The United States argues that the federal government’s right to use discretion is necessary because of the need to wisely allocate enforcement resources and because of the Executive branch’s needs to handle any repercussions stemming from decisions regarding aliens. The United States contends that Arizona, through its statute, would inevitably infringe upon the Executive Branch’s discretion by being able to enforce federal immigration law without taking into account federal immigration policies.

Arizona argues that Congress intended cooperation between state and federal law enforcement officers in enforcing immigration laws. Arizona maintains that through 8 U.S.C. § 1357, Congress has made clear that state officers may enforce federal law and that federal officers should be responsive to inquiries of state officers. For instance, Arizona argues that the provision of S.B. 1070 that allows state officers to make warrantless arrests as long as there is probable cause, is constitutional because state officers have concurrent authority to arrest unlawful aliens based on federal law. Arizona contends that its officers have authority to make arrests for civil and criminal violations of immigration law, and that state officers will make such arrests in a manner that does not deviate from federal law. Arizona argues that the Ninth Circuit incorrectly found that Congress intended to allow state officers to enforce immigration policies concurrent with federal officers only either based on an agreement with the Attorney General. Arizona states that S.B. 1070 will not increase interference with federal immigration enforcement because state and local law enforcement officers already often verify immigration statuses when they conduct stops or book aliens into jail. Arizona emphasizes that states generally have the right to enforce federal laws provided there is not an explicit Congressional statement to the contrary.

States’ Ability to Punish Conduct Regulated by the Federal Government

The United States argues that provisions of S.B. 1070 give Arizona the ability to independently create state offenses and impose penalties for violations of federal law. Therefore, the United States maintains that this is not cooperative law enforcement as Arizona claims. The United States argues that requirements imposed on aliens, such as alien registration, are under the exclusive authority of the Executive Branch, and states cannot impose penalties for violations in an area where the conduct is comprehensively regulated by the federal government. The United States contends that the relationship between aliens and the government is federal in nature, as it is created and regulated by federal law, and the failure to comply with any federal requirements should not result in any state penalties. The United States argues that a violation of federal immigration law should not result in state penalties because alien registration does not implicate any state police powers. The United States contends that in similar areas of law that are also under the exclusive authority of the federal government, the Supreme Court has found that states did not have a right to impose independent penalties, and the United States argues that the Supreme Court should make a similar finding here.

The United States argues that the punishments that the Arizona statute sets forth are especially problematic because they conflict with the purposes of federal immigration law. The United States asserts that under S.B. 1070, Arizona would only punish aliens who have not obtained authorization to stay in the United States, but maintains that the federal scheme does not view unlawful presence as a crime and affords relief in at its discretion. Furthermore, the United States argues that while the INA provides that employers check an employee’s employment eligibility after he or she is hired, S.B. 1070 imposes criminal penalties for merely soliciting or applying for work. In this way, the United States contends, the statute conflicts with the federal immigration laws and their flexibility.

Arizona, on the other hand, argues that the statute is constitutional because the Supreme Court has previously found that as long as Congress has not declared that federal law preempts an entire area of law, states were free to prohibit conduct that is also prohibited under federal law. It contends that states are free to aid the federal government with national issues. Arizona asserts that because the registration provision of S.B. 1070 prohibits exactly what federal immigration law prohibits and imposes nearly identical penalties for failure to comply with registration requirements, the provision is valid. Moreover, Arizona contends that prohibiting employers from hiring unauthorized aliens is consistent with federal law’s objective of curtailing employment of unauthorized aliens, making the provisions regarding employment valid as well. Arizona argues that it has the right to regulate that particular area of immigration law because the regulation of employment falls under traditional state police powers and protecting its workers is a legitimate interest.

In asserting that federal law does not preempt the penalties imposed by S.B. 1070, Arizona emphasizes that the Supreme Court has, in previous cases, rejected the argument that the federal government’s decision not to adopt a regulation automatically prohibits states from adopting it. Arizona asserts that it should not be any different for immigration law and thus, states should be able to create regulations in areas of traditional state authority such as employment even if it affects immigration, where Congress has purposely refrained from doing so.


Petitioner the State of Arizona argues that S.B. 1070 does not clearly conflict with a federal statute, and state officials have inherent authority to engage in cooperative enforcement of federal immigration laws. Respondent the United States contends that the federal government has exclusive authority over immigration and that the Arizona law undermines important national policies.

Impact on Health, Safety, and Individual Rights

The Landmark Legal Foundation (“Landmark”) argues that Arizona provides a major access point for illicit drug and human traffickers. The United States Border Control (“Border Control”) argues that Arizona experiences violent cross-border crimes due to federal underenforcement of immigration laws.

The Center for Constitutional Jurisprudence (“the Center”) argues that the federal government has underenforced federal immigration law. The Center adds that if S.B. 1070 is not upheld and enforced, this inadequate enforcement of immigration law will threaten illegal immigrants’ wellbeing. The Center maintains that underenforcement allows illegal workers to accept unsafe working conditions, and creates an “underclass” in Arizona and other states. Freedom Watch adds that illegal immigrants will not be subjected to racial discrimination if S.B. 1070 is enforced because the statute prohibits law enforcement officers from considering an individual’s race or national origin when determining an individual’s immigration status.

The American Bar Association (“ABA”) responds that Section 2 of S.B. 1070 raises due process concerns and impermissibly places the burden of proving legal status on the detainee. According to the ABA, determining immigration status is often complicated at the federal level, sometimes leading to lengthy detainment. The ABA claims that such difficulties will be intensified at the state level, where officials have less experience with federal immigration laws.

The United States Conference of Catholic Bishops (“Catholic Bishops”) argues that S.B. 1070 threatens important federal objectives, including the promotion of family unity and human rights. The Catholic Bishops maintain that S.B. 1070 will cause more families to be separated, and will prevent some immigrants from providing for their families.

Impact on State and Federal Policy

Border Control claims that underenforcement has subjected Arizona to home invasions, kidnappings, and other crimes related to illegal immigration. Furthermore, Border Control maintains that the federal government requires the state to provide benefits for aliens, the cost of which has increased by approximately $2.7 billion due to illegal immigration.

The American Unity Legal Defense Fund (“American Unity”) states that underenforcement harms American workers. American Unity maintains that the federal government’s inadequate enforcement has contributed to unemployment and lower wages for low income workers, and that employers often choose illegal immigrants over more expensive legal workers.

Former Commissioners of the United States Immigration and Naturalization Service respond that collective enforcement will eventually create an inefficient patchwork of local immigration laws. The Former Commissioners also argue that S.B. 1070 will require the use of limited federal resources to make immigration status determinations for Arizona.

According to Madeleine K. Albright, state immigration laws like S.B. 1070 interfere with foreign relations by creating tension with other nations and causing retaliation against U.S. citizens. According to Albright, government officials in Mexico and countries in Central and South America have criticized the law, and some have warned their citizens about the dangers in traveling to the United States.


In this case, the Supreme Court will determine whether federal immigration laws impliedly preempt an Arizona statute that mandates its law enforcement officers enforce federal immigration laws along with federal officers and imposes state penalties for non-compliance with federal immigration requirements. Petitioners the State of Arizona and Janice K. Brewer, the Governor of Arizona, argue that the statute merely creates a cooperative working relationship between state and federal officers and further promotes federal immigration policy objectives. The United States argues that the statute is invalid because it gives Arizona the ability to set policies and penalties in an area where the Congress has vested exclusive authority in the federal government, and is therefore preempted. This case will have substantial implications for the balance of state and federal power in the immigration law.

Edited by 


Additional Resources 

Robert Barnes, The Washington Post: Supreme Court to Hear Challenge to Arizona’s Immigration Law (Dec. 12, 2011)

Adam Liptak, N.Y. Times: Court to Weigh Arizona Statute on Immigration (Dec. 12, 2011)

Constitutional Law Prof Blog: Supreme Court to Hear Arizona S.B. 1070 on Preemption Issue (Dec. 12, 2011)