Since its founding, the U.S. has struggled with issues of federalism and states' rights. In almost every area of law, from abortion to zoning, conflicts arise between the states and the federal government over which entity is best suited to create and enforce laws. In the last decade, immigration has been on the front lines of this debate, with states such as Arizona taking an extremely assertive role in policing immigrants within their borders. While Arizona and its notorious SB 1070 is the most visible example of states claiming expanded responsibility to make and enforce immigration...