Arizona v. United States
Based on Wikipedia: Arizona v. United States
When Arizona Tried to Become Its Own Immigration Enforcer
In the spring of 2010, something extraordinary happened in American law. Arizona decided it was tired of waiting for the federal government to do something about illegal immigration, so it passed a law attempting to take matters into its own hands. The backlash was immediate and fierce—tens of thousands of protesters flooded the streets of seventy American cities, a cardinal of the Roman Catholic Church marched in Los Angeles, and the United States Department of Justice sued the state of Arizona.
The resulting Supreme Court case, decided in 2012, would become a landmark ruling on one of the most fundamental questions in American government: Who gets to decide how immigration law works in this country?
The Law That Started It All
On April 23, 2010, Arizona Governor Jan Brewer signed Senate Bill 1070, which its supporters gave the rather unwieldy name "Support Our Law Enforcement and Safe Neighborhoods Act." The law did several things that had never been done before at the state level.
It made it a state crime—a misdemeanor—for an undocumented immigrant to be in Arizona without carrying federal registration documents. Think about that for a moment. The federal government already required certain immigrants to carry registration papers, but Arizona was now making it a separate state offense to violate that federal requirement. It was like a city creating its own local crime for not paying federal income taxes.
The law also authorized Arizona's state and local police to enforce federal immigration laws. Police officers could now investigate a person's immigration status during any lawful stop, detention, or arrest if they had "reasonable suspicion" that the person was in the country illegally.
And it penalized anyone who knowingly sheltered, hired, or transported undocumented immigrants.
The Streets Erupt
The reaction was swift and emotional.
On May 1, 2010—International Workers' Day—protests exploded across America. In Los Angeles, somewhere between fifty and sixty thousand people marched through the streets. Cardinal Roger Mahony, one of the most prominent Catholic leaders in America, joined them. Protesters waved Mexican flags and chanted "Sí se puede"—Spanish for "Yes, we can," a slogan borrowed from the farmworkers' movement of the 1970s.
Dallas saw twenty-five thousand protesters. Chicago and Milwaukee each drew more than five thousand. Smaller cities across the country hosted rallies of around a thousand people each.
What made these protests particularly interesting was their dual target. Yes, protesters were angry at Arizona. But many also directed their frustration at President Obama, whose administration had not delivered on promises of immigration reform. Signs reading "Hey Obama! Don't deport my mama" captured this divided anger perfectly.
The Constitutional Question at the Heart of It All
On July 6, 2010, the Justice Department filed suit against Arizona, and the core argument was elegant in its simplicity: immigration is a federal matter, not a state one.
The Constitution gives Congress the power to "establish an uniform Rule of Naturalization." Notice that word: uniform. The framers wanted immigration rules to be the same everywhere in the country. A patchwork of different state immigration policies would create chaos—imagine if California welcomed certain immigrants while Arizona arrested them, or if Texas had different rules than New Mexico.
This principle is called federal preemption, drawn from the Supremacy Clause of the Constitution, which establishes that when federal and state laws conflict, federal law wins. It's not even close—the federal law doesn't just have an advantage, it completely displaces the state law.
But Arizona had a counterargument. The state pointed to a 1976 Supreme Court case called De Canas v. Bica, which had allowed states some room to regulate in the immigration space. Arizona argued it wasn't trying to replace federal immigration law—it was trying to help enforce it. The federal government wasn't doing enough, so Arizona would step in and fill the gap.
A Nation Takes Sides
The case quickly became a proxy war in America's larger immigration debate.
Nine states—Michigan, Florida, Alabama, Nebraska, Pennsylvania, South Carolina, South Dakota, Texas, and Virginia—plus the Commonwealth of the Northern Mariana Islands filed a legal brief supporting Arizona. Their argument was pointed: the Obama administration was selectively enforcing immigration laws, leaving states like Arizona to deal with the consequences. "The States have lost control over their borders," they wrote, "and are left to guess at the reality of the law."
Eighty-one members of Congress also filed a brief backing Arizona.
But here's where it gets interesting. Eleven Latin American countries—Argentina, Bolivia, Chile, Colombia, Costa Rica, El Salvador, Guatemala, Mexico, Nicaragua, Paraguay, and Peru—filed their own brief supporting the United States government against Arizona. It's not often you see foreign nations formally weighing in on American court cases, but immigration is inherently international, and these countries had citizens whose treatment hung in the balance.
The First Round: Judge Bolton's Ruling
Before the law could even take effect, federal Judge Susan Bolton blocked its most controversial provisions. Her reasoning focused on a practical problem: if every local police department in Arizona started checking immigration status, the federal government would be overwhelmed with requests.
Federal resources will be taxed and diverted from federal enforcement priorities as a result of the increase in requests for immigration status determination that will flow from Arizona.
This was a clever argument. Even if Arizona's law wasn't directly contradicting federal law, it was interfering with federal priorities. The federal government had limited resources and had made decisions about how to deploy them. Arizona was about to throw a wrench into that entire system.
Governor Brewer called it "a temporary bump in the road" and immediately promised to appeal.
The Ninth Circuit Weighs In
The appeal went to the Ninth Circuit Court of Appeals, which covers Arizona and is one of the largest and most influential appellate courts in the country. On November 1, 2010, a three-judge panel heard arguments.
The panel split. Judges Richard Paez and John Noonan voted to uphold Judge Bolton's injunction, agreeing that Arizona had intruded upon federal territory. Judge Carlos Bea dissented in part.
Judge Noonan wrote a particularly memorable concurrence. "The Arizona statute before us has become a symbol," he observed. "For those sympathetic to immigrants to the United States, it is a challenge and a chilling foretaste of what other states might attempt."
He was right about that. Other states were watching closely, considering their own versions of SB 1070.
The Supreme Court Takes the Case
Governor Brewer made a bold choice: rather than ask for a rehearing before the full Ninth Circuit—which would have been the normal next step—she appealed directly to the Supreme Court. It was a gamble. The Supreme Court only agrees to hear a tiny fraction of the cases brought before it. But Brewer was betting that the justices would recognize the national importance of the immigration question.
She was right. In December 2011, the Supreme Court announced it would review Arizona's law. Oral arguments were scheduled for April 25, 2012.
One notable absence: Justice Elena Kagan recused herself from the case. As Solicitor General under President Obama, she had been involved in the federal government's legal strategy. Judicial ethics required her to sit this one out, leaving only eight justices to decide the case.
The Court's Decision
On June 25, 2012, the Supreme Court handed down its ruling. It was neither a complete victory for Arizona nor a complete victory for the federal government.
Justice Anthony Kennedy wrote the majority opinion, joined by Chief Justice John Roberts and Justices Ruth Bader Ginsburg, Stephen Breyer, and Sonia Sotomayor. The Court struck down three of the four challenged provisions—but it let one controversial piece stand, at least for the time being.
What the Court Struck Down
Section 3 of Arizona's law, which made it a state crime to fail to register with the federal government, was preempted. The Court's reasoning was stark: "the Federal Government has occupied the field of alien registration." When the federal government completely occupies a legal field, states can't add anything—"even complementary state regulation is impermissible." Arizona wasn't just conflicting with federal law; it was treading on ground that belonged exclusively to the federal government.
Section 5, which made it a state crime to seek work without authorization, was also preempted, but for a different reason. Congress had made a deliberate choice not to criminalize unauthorized work-seeking. That wasn't an oversight—it was policy. By criminalizing what Congress had intentionally left legal, Arizona was standing "as an obstacle to the objectives of Congress."
Section 6 was perhaps the most aggressive part of Arizona's law. It allowed state police to arrest anyone they believed might be subject to removal from the country, without a warrant. The Court found this went too far. Being in the country illegally isn't actually a crime in most circumstances—it's a civil violation. Section 6 would have given state officers "even greater authority to arrest aliens on the basis of possible removability than Congress has given to trained federal immigration officers."
That last point deserves emphasis. Arizona was trying to give its local police more power than the federal agents who specialized in immigration enforcement. The Court saw this as an overreach.
What the Court Let Stand—Sort Of
Section 2(B) survived, but with significant limitations. This was the provision requiring police to check immigration status during lawful stops if they had reasonable suspicion someone was in the country illegally.
The Court allowed this provision to go into effect, but Justice Kennedy issued a warning: police could not detain someone for an extended period simply because they lacked immigration documents. And if racial profiling occurred, those cases could proceed through the courts.
"This opinion does not foreclose other preemption and constitutional challenges to the law as interpreted and applied after it goes into effect," Kennedy wrote. In other words: we're letting this part of the law start operating, but we'll be watching.
The Dissents
Justices Antonin Scalia, Clarence Thomas, and Samuel Alito each wrote separate opinions disagreeing with parts of the majority's reasoning. None of them joined each other's opinions—a sign of how fractured the conservative position was.
Justice Scalia's dissent was the most forceful. He would have upheld all four provisions, arguing that states have an inherent sovereign power to exclude people from their territory. "As a sovereign, Arizona has the inherent power to exclude persons from its territory," Scalia wrote, "subject only to those limitations expressed in the Constitution or constitutionally imposed by Congress."
This was a fundamentally different vision of American federalism. In Scalia's view, states retained substantial independent authority over who could be within their borders. The federal government might set immigration policy, but states could enforce it—and even supplement it—as they saw fit.
The Broader Principle
At its core, Arizona v. United States was about something larger than immigration policy. It was about the nature of American federalism and the balance of power between state and federal governments.
Justice Kennedy's majority opinion embraced an expansive view of federal authority over immigration, describing it as "broad" and "undoubted." This authority came from two sources. First, the Constitution explicitly gives Congress power over naturalization. Second, controlling immigration is inherently connected to foreign relations—deciding who can enter the country affects relationships with other nations. And foreign relations have always been understood as primarily a federal responsibility.
But Kennedy also acknowledged Arizona's legitimate concerns. He noted that highway signs south of Phoenix actually discouraged public travel because of dangerous smuggling activities. Arizona wasn't imagining a problem—it was dealing with a real one. The question was whether the state could unilaterally decide how to address it.
The answer, for the most part, was no.
What Made This Case Different
Preemption cases come before the Supreme Court regularly, but Arizona v. United States had unusual features that made it particularly significant.
First, it involved a direct confrontation between a state and the federal executive branch. The Justice Department wasn't defending a statute that Arizona happened to conflict with—it was actively arguing that Arizona was undermining federal enforcement discretion. The Obama administration had made choices about immigration priorities, and Arizona was trying to override those choices.
Second, the case came at a moment of intense national debate about immigration. Millions of undocumented immigrants lived in the United States, and Congress had failed repeatedly to pass comprehensive reform. States like Arizona felt abandoned. Whether you saw SB 1070 as a reasonable response to federal inaction or as an unconstitutional power grab depended largely on your politics.
Third, the ruling had implications far beyond Arizona. Other states had passed or were considering similar laws. The Supreme Court's decision would determine whether this approach was viable anywhere.
The Aftermath
The decision left both sides claiming partial victory. Supporters of the law celebrated that the "show me your papers" provision survived. Opponents celebrated that the most aggressive parts of Arizona's approach had been invalidated.
But the larger story was about limits. States could not criminalize what federal law left alone. States could not create enforcement mechanisms that exceeded federal ones. States could not create a patchwork of immigration policies that disrupted federal priorities.
The federal government's authority over immigration remained supreme—even when states felt the federal government wasn't using that authority effectively.
A Question That Persists
More than a decade later, the tensions that produced Arizona v. United States haven't disappeared. Immigration remains one of the most contentious issues in American politics. States continue to push the boundaries of what they can do, sometimes in the direction of stricter enforcement, sometimes in the direction of sanctuary policies that limit cooperation with federal authorities.
The fundamental question the case addressed—who gets to control immigration policy in a federal system—remains contested in American politics and law. But the Supreme Court's answer in 2012 established an important principle: however frustrated states might become with federal policy, the Constitution assigns this particular power to the national government.
Arizona tried to go it alone on immigration. The Supreme Court said that's not how American federalism works.