Like the decision released Monday, none of the legal battles will settle the nation's raging political debate on immigration, where President Barack Obama and Republican challenger Mitt Romney are deeply at odds.
The court's decision lands in the middle of a presidential campaign in which Obama has been heavily courting traditionally Democratic-leaning Latino voters and Romney has been struggling to win their support after taking a hard line on illegal immigration in a drawn-out primary campaign.
The conservative-dominated high court found much of Arizona's immigration law unconstitutional, but it ruled that one part would stand - the requirement that police check the status of someone they suspect is not in the U.S. legally. Even there, the justices said the provision could be subject to legal challenges as the state that shares a long border with Mexico goes forward.
Obama said he was pleased with the ruling but objected to the provision that was left standing. "No American should ever live under a cloud of suspicion just because of what they look like," he said in a statement.
Romney said the law has "become a muddle" and released a statement saying, "I believe that each state has the duty - and the right - to secure our borders and preserve the rule of law, particularly when the federal government has failed to meet its responsibilities."
The Arizona case focused on whether states can adopt their own measures to deal with an estimated 11 million illegal immigrants in the face of federal inaction on comprehensive reforms.
The Obama administration sued to block the Arizona law soon after its enactment two years ago, calling it an unconstitutional intrusion into an area under Washington's control. Federal courts had refused to let the four key provisions take effect.
But other states were inspired by Arizona's move, and Alabama, Georgia, Indiana, South Carolina and Utah adopted variations of its law, in some cases going even further. Alabama required that public schools verify the citizenship status of new students, and Indiana allowed police to arrest anyone who had been ordered by federal authorities to be detained or deported - even if they were not suspected of any other crime. Groups including the American Civil Liberties Union said the provision gave police unprecedented arrest powers.
Parts of the states' laws have been on hold pending the outcome of the Arizona case. Now challenges to them likely can move forward in lower courts.
The Supreme Court struck down three major Arizona's requirements: requiring all immigrants to obtain or carry immigration registration papers, making it a crime for an illegal immigrant to seek or hold a job and allowing police to arrest suspected illegal immigrants without warrants.
"This is a massive defeat for those who believe states can regulate immigration," said Charles Kuck, an Atlanta immigration attorney and former president of the American Immigration Lawyers Association. "I think it's funny that anybody could read that decision and come to any other conclusion."
But several lawmakers and civil rights groups said the part of the law left in place by the high court was an invitation to racial profiling. The court was unanimous on allowing the "show me your papers" immigration status check to go forward, but police officers are prohibited from arresting people on minor immigration charges.
Arizona Gov. Jan Brewer, a Republican, said the ruling marked a victory for people who believe in the responsibility of states to defend their residents.
But Justice Anthony Kennedy, joined in his majority opinion by conservative Chief Justice John Roberts as well as three liberal justices, said the impasse in Washington over immigration reform did not justify state intrusion.