WASHINGTON (AP) - Key parts of Arizona's immigration law have been struck down by the Supreme Court -- but not the provision requiring police to check the immigration status of someone they suspect is in the United States illegally.

Even there, though, the justices said the provision could face additional legal challenges. And while upholding the "show me your papers" requirement for now, the justices took the teeth out of it -- by prohibiting police officers from arresting people on minor immigration charges.

The ruling was unanimous in allowing the status check to go forward. But the court was divided on striking down the other provisions.

The provisions that were struck down include one that required all immigrants to obtain or carry immigration registration papers. Also rejected was a provision making it a state criminal offense for an illegal immigrant to seek work or hold a job. And the justices said police can't arrest suspected illegal immigrants without warrants.

The Obama administration had sued to block the Arizona law soon after it was enacted two years ago.

Five other states have adopted variations on the law. Parts of those were on hold pending the outcome of this case.

Justices Antonin Scalia and Clarence Thomas said they would have allowed all of the challenged provisions to take effect.