On Monday the U.S. Supreme Court rejected most of Arizona's tough 2010 border-control law but affirmed the provision which empowers police to investigate the residency status of anyone they stop or arrest. "Arizona is saying it is unfriendly to illegal immigrants and that part of [its law] was left standing," said Peter Spiro, a professor at Temple's Beasley School of Law. "But in terms of its practical influence it was clearly defanged" because the rest of the court's opinion broadly validates "the near-exclusive federal power over immigration."