Understanding the Constitution: How States May Respond to Illegal Immigration—Part IV

The issue comes up this way: First, a state makes a decision traditionally associated with defensive war. It may erect barriers, restrict foreign goods, control immigration, or hold prisoners. Then the federal government or private parties sue the state, claiming these subjects are “preempted” by federal law, and the state may do nothing. Federal preemption arguments have had more success than the Constitution justifies.