In a time of polarization, states may introduce salutary pluralism into an executive-dominated regime. With partisan divisions sidelining Congress, states are at once principal implementers and principal opponents of presidential policies. As polarization makes states more central to national policymaking, however, it also poses new threats to their ability to act. This Essay cautions against recent efforts to preempt state control over state officials and to require states to follow other states’ policies, using sanctuary jurisdictions and the pending federal Concealed Carry Reciprocity Act as examples.

* Professor of Law, Columbia Law School.