The Supreme Court stepped into the fight Monday over a tough Arizona law that requires local police to help enforce federal immigration laws - pushing the court deeper into hot, partisan issues of the 2012 election campaign.
The court's election-year docket now contains three politically charged disputes, including President Barack Obama's health care overhaul and Texas redistricting.
The debate over immigration already is shaping presidential politics, and now the court is undertaking a review of an Arizona law that has spawned a host of copycat state laws targeting illegal immigrants.
The court will review a federal appeals court ruling that blocked several provisions in the Arizona law. One of those requires that police, while enforcing other laws, question a person's immigration status if officers suspect he is in the country illegally.
The case is the court's biggest foray into immigration law in decades, said Temple University law professor Peter Spiro, an expert in that area.
The Obama administration challenged the Arizona law by arguing that regulating immigration is the job of the federal government, not states. Similar laws in Alabama, South Carolina and Utah also are facing administration lawsuits. Private groups are suing over immigration measures adopted in Georgia and Indiana.
"This case is not just about Arizona. It's about every state grappling with the costs of illegal immigration," Arizona Gov. Jan Brewer, a Republican, said following the court's announcement Monday.
Fifty-nine Republicans in Congress, including presidential candidate Michele Bachmann, filed a brief with the court backing the Arizona law.
The immigration case, like the challenge to Obama's health care overhaul, pits Republican-led states against the Democratic administration in an argument about the reach of federal power. The redistricting case has a similarly partisan tinge to it, with Republicans who control the state government in Texas facing off against Democrats and minority groups that tend vote Democratic.
In the immigration arena, the states say that the federal government isn't doing enough to address a major problem and that border states are suffering disproportionately.
The issue has been widely discussed by the Republican candidates for president. They have mostly embraced a hard line to avoid accusations that they support any kind of "amnesty" for the some 12 million illegal immigrants estimated to be living in the U.S.
Newt Gingrich was most recently criticized by his opponents for saying he would grant legal status to some with longstanding family and community ties, and Gingrich has since endorsed the South Carolina law that allows police to demand a person's immigration status. That law is among the four state laws that have been challenged by the administration.
Brewer signed the Arizona immigration measure into law in April 2010. The administration sued three months later to block it from taking effect.
In April, a three-judge panel of the 9th U.S. Circuit Court of Appeals in San Francisco upheld a federal judge's ruling halting enforcement of several provisions of the law. Among the blocked provisions: requiring all immigrants to obtain or carry immigration registration papers; making it a state criminal offense for an illegal immigrant to seek work or hold a job and allowing police to arrest suspected illegal immigrants without warrants.
In October, the federal appeals court in Atlanta blocked parts of the Alabama law that forced public schools to check the immigration status of students and allowed police to file criminal charges against people who were unable to prove their citizenship.
Lawsuits in South Carolina and Utah are not as far along.
The administration argued that the justices should have waited to see how other courts ruled on the challenges to other laws before getting involved. Still, following the court's announcement Monday, White House spokesman Jay Carney said, "We look forward to arguing our point of view in that case when the time comes."
Spiro, the Temple University immigration expert, said the court easily could have passed on the Arizona case for now. "They could have waited for the more extreme case to come from Alabama, which really outflanked the Arizona law," Spiro said.
He predicted the court would uphold the police check of immigration status but perhaps not the measure making it a crime to be without immigration documents.
Arguments probably will take place in late April, which would give the court roughly two months to decide the case.
Justice Elena Kagan will not take part case, presumably because of her work on the issue when she served in the Justice Department in the Obama administration.
The case is Arizona v. U.S., 11-182.