Arizona Immigration Law Facts: SB 1070, Section 2(B), and Prop 314

Arizona SB 1070, signed into law in April 2010, was the most aggressive state immigration enforcement law of its era, and most of it no longer stands. The U.S. Supreme Court struck down three of its four contested provisions in 2012, leaving only the “show me your papers” requirement in place, and even that survived with a warning that future challenges could succeed if the law were enforced in ways that led to prolonged detentions or civil rights violations.¹ Arizona voters added a new layer in November 2024 by approving Proposition 314, which creates additional state-level immigration crimes, though its most far-reaching provisions remain dormant by design.

What SB 1070 Originally Did

The Support Our Law Enforcement and Safe Neighborhoods Act declared a state policy of “attrition through enforcement” and barred local governments from limiting cooperation with federal immigration authorities.² Four provisions drew the federal challenge that would reach the Supreme Court:

Section 2(B): Required officers to make a reasonable attempt to verify immigration status during any lawful stop, detention, or arrest where they had reasonable suspicion the person was unlawfully present.
Section 3: Made it a state crime to fail to carry federal alien registration documents.
Section 5(C): Made it a misdemeanor for an unauthorized immigrant to seek or perform work in Arizona.
Section 6: Authorized state and local officers to arrest someone without a warrant if they had probable cause to believe the person had committed an offense that made them removable from the country.³

A week after Governor Jan Brewer signed the bill, the legislature passed HB 2162, which added an explicit prohibition on using race, color, or national origin to enforce the law except as permitted by the U.S. or Arizona Constitution. HB 2162 also narrowed Section 2(B) from any “lawful contact” to a “lawful stop, detention, or arrest.”⁴

What the Supreme Court Struck Down

The federal government sued almost immediately, arguing that the Constitution gives Washington authority over immigration and that Arizona’s law intruded on that territory. The Supreme Court decided the case in 2012 on federal preemption grounds. The core principle: when Congress has built a comprehensive regulatory system in an area, states cannot create their own parallel or conflicting rules, even ones that share the same goals.⁵

Three provisions fell:

Section 3 (registration documents): Congress had fully occupied the field of alien registration through what the Court called a “single integrated and all-embracing system.” Even a state law that mirrored federal requirements was preempted.
Section 5(C) (working without authorization): Federal law addressed unauthorized employment through the Immigration Reform and Control Act of 1986, which deliberately imposed criminal penalties on employers but only civil penalties on workers. Arizona’s criminal penalty on workers conflicted with the balance Congress chose.
Section 6 (warrantless arrests): Letting state officers arrest people based only on probable cause of removability inserted the state into the federal removal process without federal direction. The Court noted that being removable is not itself a federal crime, and that the federal government has discretion over when to pursue removal.⁵

The reasoning matters beyond Arizona. States cannot create their own criminal penalties in areas where Congress has built a comprehensive enforcement framework, even where state law appears to support federal goals. That principle has shaped every state-level immigration bill since.

What Survived: Section 2(B)

The only contested provision left standing was Section 2(B), the requirement that officers check immigration status during a lawful stop when they have reasonable suspicion the person is unlawfully present.³ The Court’s reasoning was cautious. The majority said it would be “inappropriate to assume” the provision would be applied in a way that conflicts with federal law before state courts had a chance to interpret it. The opinion also warned that detaining people solely to verify immigration status “would raise constitutional concerns” and “disrupt the federal framework,” leaving the door open for future challenges based on how the law was actually enforced.¹

In practice, officers can run an immigration status check during a stop they already have legal grounds to make, such as a traffic violation. What they cannot do is extend the stop beyond the time needed to handle its original purpose just to wait for an immigration response.

How Section 2(B) Is Applied Today

After the ruling, the Arizona Attorney General issued an advisory opinion setting enforcement standards. The guidelines impose several concrete limits:

Officers cannot use race or ethnicity to develop reasonable suspicion that someone is unlawfully present.
Officers cannot stop someone solely to investigate immigration status.
Officers cannot hold someone longer than necessary to address the original reason for the stop just to run an immigration check.⁶

The guidelines also create a presumption of lawful status. A person is presumed lawfully present if they show a valid Arizona driver’s license, a valid Arizona non-operating identification license, a valid tribal enrollment card, or any government-issued ID from a jurisdiction that requires proof of legal presence before issuing it. When an officer deviates from the policy, they must notify a supervisor at the first reasonable opportunity.⁶ These constraints narrow Section 2(B) considerably from the broad power critics initially feared.

When Enforcement Went Wrong: Melendres v. Arpaio

The risk the Supreme Court flagged when it let Section 2(B) survive played out in Maricopa County. In Melendres v. Arpaio, a federal court found that the sheriff’s office under Joe Arpaio maintained a “custom, policy and practice of racially profiling Latino drivers and passengers” and stopping them under the guise of enforcing immigration-related laws.⁷

The court permanently barred the sheriff’s office from detaining Latino vehicle occupants based only on a reasonable belief they were unauthorized, from using race or Latino ancestry as a factor in deciding whether to stop a vehicle, and from holding people stopped for traffic violations longer than needed to resolve the violation without independent suspicion of a separate crime. It also appointed an independent monitor and ordered changes to training, traffic-stop documentation, and deputy supervision.⁷ The case remains under active federal oversight.

Proposition 314 and What’s Enforceable Now

Arizona voters approved Proposition 314, the Secure the Border Act, in November 2024. It creates new state-level immigration crimes that go beyond what SB 1070 attempted, though several provisions were written to stay dormant until courts uphold similar laws elsewhere.

Currently in effect:

A person who is not lawfully present and knowingly submits false documentation when applying for federal, state, or local public benefits commits a class 6 felony.
Submitting false information to an employer to evade E-Verify detection is a class 1 misdemeanor for a first offense and a class 6 felony for subsequent offenses.
Knowingly selling fentanyl that was not lawfully manufactured or imported and that caused someone’s death is a class 2 felony.⁸

The most aggressive provisions are not in effect. Those would make it a state crime for a non-citizen to enter Arizona from a foreign country anywhere other than a lawful port of entry and would authorize state officers to order deportations. A trigger provision built into Proposition 314 ties these powers to the outcome of similar laws in other states. Until a federal court upholds one of those laws, Arizona’s entry and removal provisions stay dormant. The Fifth Circuit Court of Appeals was expected to rehear the challenge to the Texas version in early 2026.⁸ Two advocacy organizations challenged Proposition 314 in state court in 2025, but a judge dismissed the challenge, finding that the dormant provisions were not yet ripe for review.

1
Justia. Arizona v. United States, 567 US 387 (2012)
2
Arizona Legislature. Arizona Senate Bill 1070
3
Arizona Legislature. Arizona Senate Bill 1070
4
Arizona Legislature. SB 1070 as Amended by HB 2162
5
Legal Information Institute. Arizona v. United States
6
Arizona Attorney General’s Office. Advisory Model Policy for Law Enforcement Applying SB 1070
7
United States Court of Appeals for the Ninth Circuit. Melendres v. Arpaio
8
Arizona Legislature. Proposition 314 Analysis