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?

The answer to both those questions is most likely “No.” These self-quarantine requirements are legitimate exercises of states’ power to protect their people’s health against the coronavirus pandemic.

States have “police power,” the broad authority to do what is necessary to provide for their people’s general health and welfare. But there are two relevant limitations on that power: the commerce clause and the privileges and immunities clause.

Both can be thought of as anti-discrimination rules. The commerce clause (by judicial interpretation, not its text) prevents states from discriminating against the commerce of other states, and the privileges and immunities clause prevents states from discriminating against the citizens of other states. It also protects the right to travel between the states from unreasonable restrictions.

We’ll start with the commerce clause because its dense body of case law is a useful guide in interpreting the privileges and immunities clause, which lacks a similarly rich judicial treatment in this area.

The Supreme Court has long upheld quarantine laws against commerce clause challenges. In Oregon-Washington Railroad v. Washington (1926), for example, the Supreme Court recognized that “it is well settled that a state, in the exercise of its police power, may establish quarantines against human beings, or animals, or plants” that may spread disease to the state even if those quarantines negatively affect interstate commerce.

The test (articulated in Pike v. Bruce Church, 1970) is whether the negative effect on commerce is incidental to an evenhanded effort to address a legitimate public interest. Under that test, these travel restrictions are fine. Texas, for instance, is not discriminating against Louisiana’s commerce, but protecting Texans from the real threat that travelers from Louisiana — which, at the time of this writing, has thousands of more cases than Texas’s other neighbors — will spread the disease in Texas.

As the commerce clause prevents discrimination against other states’ commerce, the privileges and immunities clause prevents discrimination against other states’ citizens. Unlike the commerce clause, however, there are no cases squarely addressing quarantine laws under the privileges and immunities clause.

Nevertheless, these laws are almost certainly still constitutional.

For one thing, despite having considered quarantine laws on many occasions, the Supreme Court has never hinted that there might be a Privileges and Immunities Clause problem with them. In Gibbons v. Ogden (1824), the court said that the constitutionality of quarantine laws “has never, so far as we are informed, been denied.”

For another, the right to travel guaranteed by the privileges and immunities clause is not absolute. In Saenz v. Roe (1999), the Supreme Court described the right as “virtually unconditional,” but went on to explain that the rights protected against only laws that “unreasonably burden or restrict” travel. These self-quarantine requirements are not unreasonable in light of the growing number of cases in every state. In fact, there’s a strong argument that states have a compelling government interest in requiring people traveling from “hot spot” jurisdictions to self-quarantine.

Lastly, these quarantine laws do not discriminate against citizens of other states. Even the state’s own citizens are subject to the self-quarantine requirement if they leave their state and then return.

Yes, these self-quarantine laws burden out-of-state travelers more than they burden the state’s own residents, but if we use the commerce clause test as a guide (because, again, there is no clear test for the privileges and immunities clause), these restrictions are lawful.

The question would be: Are the discriminatory effects of self-quarantine laws merely incidental to evenhanded efforts to address a legitimate public interest? Absolutely.

Texas, for example, is not discriminating against Louisianans except incidentally in its efforts to halt the spread of the coronavirus. Targeting travelers from Louisiana is, at least for now, a reasonable exercise of the police power because Louisiana has much higher case numbers than any of Texas’s other neighbors.

And in Rhode Island’s case, because almost every other state has coronavirus cases, requiring travelers to self-quarantine for two weeks is a reasonable precaution.

As long as states use these self-quarantine laws in reasonable, evenhanded ways to stop the spread of coronavirus, they are almost certainly constitutional.