With sudden, fearsome ruthlessness, the pandemic has laid bare the essential weaknesses — and yes, also strengths — of America’s unique federal structure. When Washington proved slow in responding to the novel coronavirus, states including California, Ohio and New York moved aggressively, imposing stay-at-home measures, closing parks and ramping up testing to head off an even deadlier disaster. At the same time, our decentralized approach has left us with a patchwork system in which citizens in some states remain vulnerable.

With the president eager to reopen the economy May 1 — and clashing with governors over who has the authority to do so — the question of the relative power of states vs. the federal government has rarely been more important. The Constitution is largely on the side of the states. Certainly, President Trump doesn’t hold ultimate authority over local public health matters. At the same time, there are aspects of this crisis to which states simply can’t respond individually.

This past week, three groups of states announced that they will collaborate as they consider cautiously restarting their economies: California, Oregon and Washington; a coalition of seven mostly Northeastern states; and a Midwestern alliance. But they could go an important step further by establishing “interstate compacts,” a legally binding form of coordination. They could thereby retain some of the advantages of local autonomy yet also gain some of the benefits of broader larger coordination. The White House could challenge these compacts — but it’s unlikely to prevail, absent a major change to constitutional law.

States clearly need to coordinate, especially given Washington’s stumbles. Remedying testing shortages, solving the shortfalls of medical equipment and instituting measures to avoid the virus’s resurgence all cry out for collective action. States don’t want to bid against one another for medical equipment. They want to ensure they have roughly congruent lockdown rules to prevent the coronavirus from spreading across borders.

Interstate compacts could help. Like a treaty between nations, a compact is a binding agreement among a self-selected group of states — typically backed by laws passed in their legislatures.

It might seem surprising that states can make such arrangements, given that, under the Constitution, “No State shall, without the Consent of Congress … enter into any Agreement or Compact with another State.” Yet more than 120 years ago, in the landmark case Virginia v. Tennessee — which concerned a border dispute between those states — the Supreme Court recognized that it would be “the height of absurdity” to subject all interstate agreements to Congress’s whims. Instead, only compacts that “encroach upon or interfere with the just supremacy of the United States” must be endorsed on Capitol Hill, the court said.

Today, there are more than 200 interstate compacts, addressing such issues as territorial ambiguities, higher education, natural resources, climate change and transportation. People who make use of Port Authority of New York and New Jersey facilities and structures, such as the George Washington Bridge, benefit from a 1921 interstate compact. Drivers caught speeding outside their home state are penalized there anyway thanks to the 45-state Driver License Compact.

Trump has sent very mixed signals about what he expects from the states during the coronavirus crisis. “Try getting it yourselves,” he famously told them, on the subject of ventilators and other medical equipment. At the same time, when some governors balked at reopening businesses before public health officials said it would be appropriate, he (falsely) asserted “total” authority to force them to do so; finally, he conceded they could make their own choices.

Of course, states don’t need formal compacts to work together. In March, New York, New Jersey and Connecticut coordinated on “shelter in place” rules, and they will now cooperate on when and how to loosen those rules. Thirty-five states and the District have also eased medical licensure requirements in lockstep to facilitate telemedicine, after a promised federal regulation on the topic failed to materialize.

But compacts would allow for even more aggressive and legally enforceable action. Consider three possible areas of compact-enabled cooperation.

First, states can enter compacts to share medical resources and increase their supplies. Rather than waging those bidding wars governors lament, allied states would wield joint purchasing power in the medical technology market (including the international market). Washington state voluntarily shipped some ventilators to New York when it no longer needed them. But as the virus ebbs and flows in various jurisdictions, compacts would structure the currently ad hoc process of allocation.

Second, compacts make it easier to share information. States already compact nationally to trade data about the movement of parolees and probationers across state lines. Several proposed plans to restart the economy depend on monitoring the movements and contacts of infected people. It would make little sense to stop such contact tracing at state borders, but at present, such efforts are likely to be impeded by the tangle of widely varying state privacy laws regarding medical records. A compact might slice through this thicket, enabling quicker interventions. (States might also adopt consistent policies balancing privacy and public health.) Compacts could be used, as well, to accelerate large-scale random-sampling serology testing for antibodies — a necessary step to understanding the extent of public immunity.

Finally, renewed waves of infection in Singapore, Hong Kong and China underscore the danger of migration from jurisdictions with lax mitigation policies. Whereas today New Yorkers are blamed in Florida for spreading the virus, the boot will probably soon be on the other foot.

While the Constitution protects the right to interstate travel, the protection is not absolute. It’s possible to imagine a compact among states with effective stay-in-place policies that would enable travel among those states, while limiting the entry of residents of states with high or rising infection rates.

States plainly cannot bar people by race or income, even though minorities and the poor are hit harder by covid-19. Nor could restrictions on movement or liberty exceed absolutely necessary limits. But travel regulations based on robust epidemiological evidence in tandem with aggressive testing and contact tracing are likely to be upheld.

Similarly, states cannot use a compact to abrogate valid national measures. If Congress passed and funded a national testing policy, for instance, states could not use a compact to deviate from the federal rules. Nor could the states intrude if Congress enacted a vaccination mandate.

But of course, the very reason that compacts are needed now is the vacuum in federal policy. In areas where the national government is declining to act, there can clearly be no encroachment on Washington’s prerogatives.

The past two months only confirm that state reliance on the federal government during the pandemic is foolish (unless, perhaps, you happen to be a partisan ally of the White House). Absent effective national action, compacts permit coalitions of willing states to protect public health gains and prevent the backsliding that a precipitous economic reopening would allow. While Washington dallies, states should keep in mind this constitutionally permitted path to collective action.