SB 1070 has been controversial since it was passed, with opponents objecting to it discriminating against "people of color", which is absolutely 100% the case as long as you use the standard definition of "people of color", namely "people who have broken the law regardless of their actual color and/or race". In case you haven't heard of the law, here's the post I did on it when it was passed bay in May of 2010.
The judges, even those appointed by Democrats and considered to be left leaning, were not terribly friendly to the Feds argument that the States making them do their job was "totally unfair" and "like, not cool at all".
"In Wednesday’s oral arguments, Supreme Court justices showed little sympathy for the federal government’s complaint that state police officers would violate federal immigration jurisdiction if they check the status of someone they pull over. That argument is seen by legal analysts as the weakest in the government’s case against the Arizona statute.Verilli, in a breathtaking display of wit and insight, stated that "Well, you know, we're kinda busy and stuff...so...we don't really have time to deal with this whole 'invasion of illegals across our sovereign borders' thing."
Justice Antonin Scalia all but laughed the federal government’s lawyer out of the courtroom when he suggested that Arizona police officers would somehow deter the federal government from enforcing immigration by calling federal officials to ask about a person they stop. “Arizona isn’t trying to kick out anybody that the federal government hasn’t already said doesn’t belong here,” he said. “The Constitution recognizes that there is such a thing as state borders and a state can police their borders.”
Solicitor General Donald B. Verrilli Jr. said the federal government has limited resources and should have the right to determine the extent of calls it gets about possible illegal immigrants.
“These decisions have to be made at the national level,” he said.
But even Democratic-appointed justices were uncertain of that.
Only eight justices are sitting on this case, Justice Elena Kegan having recused herself (presumably due to her work on this case as solicitor general). That means that the possibility of a tie exists, which would be a de facto victory for the Administration.“I’m terribly confused by your answer,” said Justice Sonia Sotomayor, who went on to say that the federal government can always decline to pick up illegal immigrants when Arizona officials call.
Based on the comments by the various Justices during the hearing, however, it does not appear that an even split is forthcoming.