In response to the coronavirus pandemic, state governments are flexing their emergency powers. Some states have issued orders requiring people entering the state to self-quarantine for at least two weeks. Some of these orders, such as Rhode Island’s, apply to all visitors. Others, such as Texas’s, apply only to visitors from certain states with relatively high numbers of coronavirus cases (Texas singled out travel from, among other places, Louisiana and Florida, where Mardi Gras and spring break celebrations created ripe conditions for the coronavirus to spread).

These self-quarantine requirements raise constitutional questions. Do they violate the constitutional right to travel between the states? Are they unconstitutional restrictions on interstate commerce?