Hawaii is now the safest state in the United States. But our economy is in shambles and we need to figure out how to welcome tourists, without endangering life or health.

Medical and public health experts tell us that testing is key in controlling the spread of the virus. As an island state, Hawaii has unique opportunities not available in geographically contiguous regions.

In discussions of reopening the Hawaii economy, many political and media voices assert that Hawaii “cannot require” a recent, reliable negative COVID test from everyone getting off an airplane here.

As experienced law teachers, we believe that nothing in the federal Constitution, laws or administrative regulations prohibit Hawaii from requiring such tests.

In our federal system, states have broad authority and responsibility to regulate public health. In 1905, in Jacobson v. Massachusetts, the United States Supreme Court upheld state authority to require vaccinations of all adults. While many states make exceptions for medical or religious reasons, the core principle of federal deference to state judgment in the realm of health and safety remains secure.

Congress has broad power to impose federal rules on states, through the exercise of its power to regulate interstate commerce and/or to impose conditions on federal funding. But Congress has not often acted to restrict state power in relation to infectious diseases. In response to U.S. Rep. Ed Case, the Federal Aviation Administration recently stated that “the agency has no authority to either grant permission or to prohibit a local or State unit of government” from mandating pre-boarding testing of airline passengers bound for Hawaii.

There are two additional conceivable grounds on which such a law that would require a negative COVID test from people entering the state could be challenged.

First, judicial precedents that established the “Dormant Commerce Clause” prohibit states from placing an undue burden on interstate commerce. The core concern is to stop protectionist state laws that discriminate against commercial competitors from out of state to favor local business. But there are some exceptions for interests such as local health and environmental concerns. As a practical matter, therefore, if Hawaii wishes to require a reliable negative COVID test for arriving passengers and to avoid a likely, albeit ultimately unsuccessful court challenge, Hawaii ought to impose the same requirement on returning residents.

Second, there are strong principles, anchored in the federal Constitution’s Equal Protection and Privileges and Immunities Clauses, that protect citizens’ rights to travel from state to state. States may not bar people from entry because they are poor, for example. In addition, states may impose durational residency requirements for some things, such as divorce, but not for others, such as emergency medical care. States therefore must treat newcomers as “friendly visitors.” Yet states often are permitted to charge higher rates to visitors than to kamaaina, for example, and courts generally have rejected constitutional challenges to such price differentials if they are reasonable.

The most simple, effective way to open Hawaii to tourism and to protect life and health may well be to require all arriving air passengers to present a reliable negative recent test before boarding a plane for Hawaii. We are not endorsing this or any other specific proposal. Questions of detail need to be addressed. Our core point is that no federal law prohibits Hawaii from adopting this or other sensible policies to reintroduce tourism while keeping people here as healthy as possible during the current horrific pandemic.

Sylvia A. Law, of Kailua, is a New York University law professor emerita and co-director of NYU’s Arthur Garfield Hays Civil Liberties Program; Aviam Soifer is dean and professor of the William S. Richardson School of Law at the University of Hawaii-Manoa.