WASHINGTON - The US Supreme Court struck down most of Arizona's controversial new immigration law on Monday but let stand a key provision allowing officers to do spot checks of people's identity papers.
US President Barack Obama voiced concern that the top court failed to invalidate the key clause, even as he welcomed being vindicated on the wider issue of state interference into federal law on immigration matters.
"No American should ever live under a cloud of suspicion just because of what they look like," Obama said in a statement, adding that the judgment made it even more vital to tackle comprehensive immigration reform.
The Arizona law has aroused intense controversy because of a particular provision, 2(B), that requires police to stop and demand proof of citizenship of anyone they suspect of being illegal, even without probable cause.
In a victory for Obama's Republicans opponents, justices unanimously refused to strike down the key clause, as they said it was unclear, before the law's actual implementation, that it raised constitutional concerns.
"It was improper to enjoin 2(B) before the state courts had an opportunity to construe it and without some showing that 2(B)'s enforcement in fact conflicts with federal immigration law and its objectives," said the ruling, which left the matter open to future challenges.
Justices rejected a series of other provisions, including those that would have criminalized immigrants for failing to register with the federal government, or for seeking work or working without proper documents.
They also struck down a clause that would have allowed police to arrest those suspected of being deportable without a warrant.
Frank Jannuzi, head of Amnesty International's Washington office, welcomed the broader tenor of the ruling, but said: "We are disappointed that the court failed to draw a clearer line in the sand against racial profiling."
Senator Charles Schumer, chairman of the Senate subcommittee on immigration and a senior Democrat, called it "as strong a repudiation of the Arizona law as one could expect" before it goes into effect.
"The court is sending a stern warning to Arizona that the provision allowing local law enforcement to check people's immigration documents cannot be implemented in a discriminatory or draconian way, or it will be thrown out like the rest of the law."
But Brewer hailed a "legal victory" and Obama's challenger for the White House in November, Mitt Romney, used the ruling to attack the president for making broken immigration promises.
"As candidate Obama, he promised to present an immigration plan during his first year in office. But four years later, we are still waiting," Romney said in a statement.
Obama's so far unfulfilled 2008 vow to bring more than 10 million illegal immigrants out of the shadows, which is opposed by conservatives, is emerging as a key issue in the 2012 election, as he courts vital Hispanic voters.
Earlier this month, Obama infuriated illegal immigration hawks by offering those brought to America illegally, between the ages of 16 and 30, work permits and a two year stay of deportation proceedings.
The Supreme Court ruling on immigration comes amid fevered anticipation of an even weightier decision on the constitutionality of Obama's signature domestic policy achievement, health care reform.
That ruling, which also has major implications for Obama's re-election chances, is now expected to come on Thursday.
Lower courts last year opted to strike sections of the Arizona law they said would place a burden on legal resident aliens in the Mexico-border state, where a third of the 6.6 million people are foreign-born and more than 400,000 are illegal immigrants.
Brewer, who earlier this year was caught on camera pointing her finger in Obama's face in what looked to be a testy exchange on an airport tarmac, asked the top court to reinstate the suspended sections.
The broad decision, written by Justice Anthony Kennedy, was approved by five votes to three. The move to uphold, for now, the status checks was unanimous.
Mexico and 17 other countries have filed arguments with the Supreme Court opposing the law. At least 36 US states have introduced legislation with elements similar to those in Arizona.