 The Supreme Court overturned three important provisions of Arizona's immigration law but upheld one important provision known as show me your papers. This provision allows police to check the immigration status of anybody they arrest, stop or detain. The Supreme Court reaffirmed a long-standing doctrine that the federal government is in charge of immigration policy and that the states, when they try to attach additional burdens to immigration, they are violating the federal government's jurisdiction. This is important because in the last couple of years, the Supreme Court has shown more favor towards just the Scalia's approach, which is that states always have the right to make immigration policy, or just the Salido's approach, which is that states have the right to make immigration policy as long as Congress hasn't explicitly told them that they can't. Either of these interpretations of the law would have opened the door to states basically setting up their own immigration regimes so that the lives not just of undocumented immigrants and illegal immigrants, not just their lives, would be different from state to state. But even the lives of legal immigrants would be different from state to state, that an immigrant could not expect the same treatment when they lived in Montana, as when they lived in Michigan, or as when they lived in Maryland. And that would be a very significant change in American law. The Supreme Court closes the door on that possibility by reaffirming that the federal government is in charge of immigration.