WASHINGTON The Supreme Court's promised ruling next year on Arizona's immigration crackdown could turn on how much a state can intrude on federal government enforcement powers.
The country's highest court agreed on Monday to decide whether federal immigration laws take precedence and so preempt Arizona's law boosting the power of local police to crack down on illegal immigrants.
Oral arguments are likely in April and a ruling by late June.
The Arizona law, passed in 2010, requires police to check the immigration status of anyone they detain and suspect of being in the country illegally. Other parts require immigrants to carry their papers at all times and ban people without proper documents from soliciting for work in public places.
Arizona Republican Governor Jan Brewer argues the state law authorizes cooperation with the U.S. government and that its sanctions consciously parallel federal law.
The U.S. government's top Supreme Court lawyer, Donald Verrilli, disagrees. He says the provisions do not represent a cooperative effort to enforce federal immigration law but "are designed to establish Arizona's own immigration policy."
The U.S. Constitution reserves certain powers to the federal government, certain powers to state governments and in some instances they can share powers, depending on the law.
A key issue is the legal doctrine of preemption, derived from what is known as the Constitution's Supremacy Clause and interpreted to mean that federal laws - even federal agency regulations - trump conflicting state laws.
Preemption can be express or implied.
Stephen Wermiel, who teaches constitutional law at American University in Washington, said the case involved implied preemption, meaning Congress did not make its intent entirely clear that all state laws were barred when it adopted major federal immigration laws.
The court has decided at least 10 preemption cases since early 2008, including ones on such products as prescription drugs, medical devices and car seatbelts, and the results have been mixed, he said.
The most relevant preemption ruling may be from May, when the court divided along ideological lines and upheld by a 5-3 vote a different Arizona law that penalizes businesses for hiring illegal immigrants, Wermiel said.
"It seems to me the case for preemption is stronger (in the pending case than in the one from May) because this goes more to the heart of immigration enforcement," Wermiel said.
"The argument that the state is not just helping, but pursuing its own agenda, seems a weightier argument," he said.
Ilya Shapiro, a senior fellow and editor-in-chief of the Cato Institute's Supreme Court review, countered that the state laws were constitutional, merely mirroring federal law and not conflicting with or intruding on U.S. immigration authority.
After the ruling, "states will know how far they can go in addressing issues relating to illegal immigrants, whether the concern is crime, employment opportunities, registration requirements or even co-called sanctuary cities," he said.
Peter Spiro, a Temple University law professor who specializes in immigration law, predicted a mixed ruling.
He said the court would likely uphold an Arizona provision that police, when stopping an individual, must try to determine that person's right to be in the United States if suspected of being illegal.
But Spiro said there were limits on how far the court would go and predicted it would reject a provision making it a crime to be without immigration documents because it conflicts with federal law, which makes it a civil violation.
He said the court could be more accommodating of state immigration measures than in the past for two main reasons.
"First, the failure of comprehensive immigration reform at the federal level is an important part of the landscape," he said. "Second, the right-side of the court has had a long-standing federalism agenda to give the states more room as a general matter."
The case will be decided by eight of the nine Supreme Court members. Justice Elena Kagan has recused herself, presumably because she worked on the case in her previous job as the Obama administration's solicitor general.
Justice Anthony Kennedy, a moderate conservative who often controls the outcome on the divided court, could cast the decisive vote, although in some past preemption cases the court has not split along the usual ideological lines.
A ruling for Arizona could influence laws in five other states facing legal challenges and prompt more states to adopt tougher immigration measures.
A ruling for the Obama administration could vindicate its challenge to the law on grounds the federal government has exclusive control over immigration policy and enforcement.
It will be a pivotal time for President Barack Obama, a critic of the Arizona law, as he seeks re-election in 2012 and counts on support from Hispanics. Many of the illegal immigrants at issue are from Mexico.
Political divisions run deep over the country's estimated 11 million illegal immigrants, especially in states such as Arizona that border Mexico.
The Supreme Court case is Arizona v. U.S., No. 11-182.
(Reporting by James Vicini, Editing by Howard Goller and Cynthia Osterman)