The US Supreme Court heard arguments Wednesday over a tough Arizona law that requires police to check the immigration status of people they stop for any reason – a hot button issue in the US that will likely impact on this year's presidential race.
Civil rights groups say the Arizona law and similar ones in a number of other states encourage racial profiling and ethnic stereotyping, while supporters argue the states are doing the job of a federal government that has failed to adequately deal with the 11 million illegal immigrants currently in the US.
The court is expected to issue its decision in late June, but regardless of the outcome the debate will likely have an impact on the Nov. 6 presidential elections.
Across the US, Republicans have far outpaced Democrats in pushing tough anti-immigration laws, posing potential political problems for the party and its presumed candidate Former Massachusetts Gov. Mitt Romney.
In the primary contests, Romney took the harshest anti-illegal immigration stance among the top contenders, but he has had little to say lately on the issue.
That aggressive stand has alienated many Hispanic voters, one of the electorate's fastest-growing segments.
President Barack Obama won two-thirds of the Hispanic vote in 2008, and hopes to do better this fall.
Even though the Obama administration has deported nearly 400,000 people a year, far more than previous administrations, a recent poll of Hispanic voters by the Pew Research Center found that 67 percent supported Obama, and 27 percent Romney.
Hispanic voters are especially important in a few battleground states that will help determine the election.
Arguing for the government, Solicitor General Donald Verrilli Jr. tried to convince the justices that they should view the law as inconsistent with federal immigration policy. He said the records check would allow the state to "engage effectively in mass incarceration" of immigrants lacking documentation.
Arguing for Arizona, Paul Clement said the state law mirrored federal immigration law and that the state it took action because, with its 600-kilometer border with Mexico, Arizona "bears a disproportionate share of the costs of illegal immigration."
Both liberal and conservative justices reacted skeptically to the administration's argument that the state exceeded its authority when it made the records check, and another provision allowing suspected illegal immigrants to be arrested without warrants, part of the Arizona law aimed at driving illegal immigrants elsewhere.
Chief Justice John Roberts took issue with Verrilli's characterization of the check of immigration status, saying the state merely wants to notify federal authorities it has someone in custody who may be in the US illegally.
"It seems to me that the federal government just doesn't want to know who's here illegally and who's not," Roberts said.
However, Roberts made clear at the outset of the administration's argument Wednesday that the court was looking only at state-versus-federal power, not the civil rights concerns that already are the subject of other lawsuits.
Outside the courthouse, more than 200 protesters gathered. The law's opponents made up a clear majority of the crowd, chanting and carrying signs such as "Do I Look Illegal To You?"
Arizona's Republican Gov. Jan Brewer, who signed the law two years ago, was at the court Wednesday.
Brewer told reporters she was "very, very encouraged" by the justices' questions.
Justice Elena Kagan, who was Obama's first solicitor general, is not taking part in the case, presumably because she worked on it while in the Justice Department.