WASHINGTON (CNN) - The U.S. Supreme Court ruled in favor of the U.S. government Monday in a controversial case involving an Arizona law that sought to crack down on illegal immigration.
The court struck down key parts of the Arizona law in a 5-3 ruling sure to ripple across the political landscape in a presidential election year.
The majority concluded the federal government had the power to block SB1070, which would have given local law enforcement the power to detain and question the immigration status of those believed to be in the country illegally.
The Obama administration had argued immigration matters were strictly a federal function.
The ruling is likely to have widespread implications for other states that have or are considering similar laws.
Fed up with illegal immigrants crossing from Mexico -- and what they say is the federal government's inability to stop it -- legislators in Arizona passed a tough immigration law. The federal government sued, saying that Arizona overreached.
At issue is whether states have any authority to step in to regulate immigration matters or whether that is the exclusive role of the federal government. In dry legal terms, this constitutional issue is known as pre-emption.
During an April hearing, Paul Clement, lawyer for Arizona, told the high court the federal government has long failed to control the problem, and that states have discretion to assist in enforcing immigration laws.
But the Obama administration's solicitor general, Donald Verrilli, strongly countered that assertion, saying immigration matters are under the federal government's exclusive authority and state "interference" would only make matters worse.
"If, in fact, somebody who does not belong in this country is in Arizona, Arizona has no power?" asked Justice Antonin Scalia. "What does sovereignty mean if it does not include the ability to defend your borders?"
Even liberal Justice Sonia Sotomayor told the federal governments' lawyer that key parts of his arguments were "not selling very well."
Several other states followed Arizona's lead by passing laws meant to deter illegal immigrants. Similar laws are under challenge in lower courts in Georgia, Alabama, Utah, Indiana and South Carolina. Arizona's appeal is the first to reach the Supreme Court.
Arizona is the nation's most heavily traveled corridor for illegal immigration and smuggling.
Justice Elena Kagan did not hear this case in April. Before taking the bench last year, she had been involved in the administration's initial legal opposition to the law as solicitor general.
Federal courts had blocked four elements of the state's Support Our Law Enforcement and Safe Neighborhoods Act, known as SB 1070.
A 4-4 high court split would be likely to keep the Arizona law in legal limbo, preventing the four provisions of the law from going into effect but not settling the larger constitutional questions.
The four provisions of the Arizona law that are on hold pending the decision are:
-- A requirement that local police officers check a person's immigration status while enforcing other laws if "reasonable suspicion" exists that the person is in the United States illegally.
-- A provision authorizing police to arrest immigrants without warrant where "probable cause" exists that they committed any public offense making them removable from the country.
-- A section making it a state crime for "unauthorized immigrants" to fail to carry registration papers and other government identification.
-- A ban forbidding those not authorized for employment in the United States to apply, solicit or perform work. That would include immigrants standing in a parking lot who "gesture or nod" their willingness to be employed.
During the 70-minute arguments in April, Clement faced relatively little tough questioning from left-leaning members of the bench.
"There will be a significant number of people who will be detained at the stop, or in prison, for a significantly longer period of time" if the state law is allowed to be enforced, warned Justice Stephen Breyer.
Justice Ruth Bader Ginsburg said the provision on carrying registration is especially problematic. "Congress enacted a complete registration scheme which the states cannot complement or impose even auxiliary regulations," she said. "We want the registration scheme to be wholly federal."
But the consistently tough questions were aimed at Verrilli from conservative members of the high court.
Even before the solicitor general began speaking midway through the argument, Chief Justice John Roberts framed the debate away from what has become a major complaint about the law: that it would target mostly Hispanic people for scrutiny and detention.
"I'd like to clear up at the outset what it's not about," Roberts said. "No part of your argument has to do with racial or ethnic profiling, does it?" Verrilli readily agreed.
Later the chief justice raised more serious concerns. When enforcing other law, "the person is already stopped