A divided court struck down these three major 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.
— Allowing police to arrest suspected illegal immigrants without warrants.
The vote was 6-2 against making it a state crime not to carry immigration papers and 5-3 against the other two provisions.
Justice Elena Kagan sat out the case because of her previous work in the Obama administration.
Arizona Gov. Jan Brewer said the ruling marked a victory for people who believe in the responsibility of states to defend their residents. The case, she said, "has always been about our support for the rule of law. That means every law, including those against both illegal immigration and racial profiling. Law enforcement will be held accountable should this statute be misused in a fashion that violates an individual's civil rights."
Civil rights groups that separately challenged the law over concerns that it would lead to rights abuses said their lawsuit would go on.
Even with the limitations the high court put on Arizona, the immigration status check still is "an invitation to racial profiling," said American Civil Liberties Union lawyer Omar Jadwat.
Carlos Beltran, looking for day labor work Monday in the Phoenix area, said he was glad to hear the court struck down most of the law.
"We can still be here today, find a job and go home and tell our wives we have something to eat tonight," said Beltran, who was born in the U.S. but whose parents are illegal immigrants.
With the ruling, however, Beltran said the potential for racial profiling will become worse. "I don't want to have my dad afraid of looking for a job. He has four kids. They shouldn't be afraid of trying to make a living," he said.
The Obama administration sued to block the Arizona law soon after its enactment two years ago. Federal courts had refused to let the four key provisions take effect.
The other states adopted variations on Arizona's law. Parts of those laws also were on hold pending the outcome of the Supreme Court case.
Chief Justice Roberts and Justices Stephen Breyer, Ruth Bader Ginsburg and Sonia Sotomayor joined all of Kennedy's opinion.
Scalia and Justice Clarence Thomas would have allowed all the challenged provisions to take effect. Justice Samuel Alito would have allowed police to arrest immigrants without papers who seek work, and also to make arrests without warrants.
Scalia, in an unusual move, pointed to facts not in the record before the court when he described Obama's recently announced plans to ease deportation rules for some children of illegal immigrants.
"The president said at a news conference that the new program is 'the right thing to do' in light of Congress' failure to pass the administration's proposed revision of the Immigration Act. Perhaps it is, though Arizona may not think so. But to say, as the court does, that Arizona contradicts federal law by enforcing applications of the Immigration Act that the president declines to enforce boggles the mind," Scalia said.
The case is Arizona v. U.S., 11-182.
Associated Press writer Jacques Billeaud in Phoenix contributed to this report.
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