Are we a union, or are we 50 states? States are finding themselves at odds with federal policy on a wide range of issues: immigration enforcement, marijuana legalization, environmental regulation, health issues including reproductive services and Medicaid, and social issues from gay marriage to who can use what bathroom. What are the constitutional roots of these conflicts? Why are they arising so frequently today? How will these conflicts play out — can we expect litigation, and what will that look like? How are the politics of these issues and the federal/state relationship shifting, and what is the outlook for the newly whole Supreme Court should any of these issues arrive there? Does our constitutional structure have what it will take to hold the nation together in the face of these challenges?