In a breathtaking assertion of authority, the federal government says that every 100-person plus private employer must require employees to be vaccinated for COVID-19, test weekly, or lose their job. While the federal government is within its right to encourage vaccine development, distribution, and inoculation, it cannot ignore constitutional protections and safeguards, even during national emergencies. That is what this federal vaccine-or-test mandate does, and why it’s unlawful.

The first problem with the vaccine-or-test mandate is that Congress has said nothing about one. Instead, it is a federal agency, composed of unaccountable bureaucrats, that has promulgated the mandate. This is problematic because federal agencies sit uncomfortably within the constitutional framework: They are generally considered to be part of the executive branch, but the executive branch is only given the power to enforce—not to make—law. And no one denies that the vaccine mandate has the force and effect of law; it currently threatens the livelihood of millions of American workers.

Given that federal agencies often exercise what looks a lot like a law-making power, the Supreme Court has imposed some limits on them. Under the major questions doctrine, when agencies make important policy decisions in areas that have highly significant economic, political, or social consequences—areas in which you’d expect Congress and not a bureaucrat to have the last word—the Supreme Court has required an explicit delegation of such authority from Congress. This so-called clear statement rule ensures that Congress is at the helm and superintending agency action.

Yet in this case, Congress has had nothing to do with OSHA’s vaccine-or-test mandate. The Occupational Safety and Health Act limits OSHA’s authority to workplace hazards; it does not give OSHA the authority to regulate general health hazards or general life hazards. OSHA has never required nationwide vaccination, regardless of occupation, even from illnesses that come with a higher morbidity than COVID-19. Neither has any other agency—or Congress for that matter.

Moreover, the emergency mechanism that OSHA used to impose its mandate allowed the agency to evade ordinary public notice and comment requirements. But COVID-19 cannot be considered an emergency that permits the evasion of procedural requirements two years into the pandemic.

In short, the vaccine-or-test mandate is unlawful because Congress has not itself required nationwide inoculation and because the federal courts do not lightly presume that agencies have the power to make law on issues of such social and political significance.

But there’s another problem with the mandate, and that it’s far from clear that Congress could impose nationwide COVID-19 vaccinations. The federal government possesses limited powers—only those expressly granted by the Constitution; the states and the people retain the remainder. As the Tenth Amendment reminds us, “The powers not delegated to the United States by the Constitution… are reserved to the States respectively, or to the people.”

But unlike the federal government, states on the other hand possess a general power of governing, also known as the police power, a power that pre-dates the Constitution and is not derived from it.

Why is the diffusion of power so important? It’s what secures our liberty. As James Madison explained in Federalist No. 45, the Founders intended for the government that we interact with daily to be more local, more accountable, and closer to the governed. And as Judge Bush recognized during proceedings in the Sixth Circuit, the Framers understood that the “true bulwark” of American liberty is the distribution of power between the federal branches—and between the federal and state governments.

There is, of course, no federal vaccine power. The authority to regulate public health is a quintessential police power reserved for the states. So OSHA relies instead on Congress’s authority to regulate commerce, which extends to activities that substantially affect interstate commerce. But as Chief Justice Roberts put it, the Supreme Court has never held that individuals “may be regulated under the Commerce Clause whenever enough of them are not doing something the Government would have them do.” The Framers never contemplated that the Commerce Clause—a clause that occasioned little controversy or debate—would transform every issue into a federal one.

This was made clear in the debate over Obamacare, when the Obama Administration argued that because everyone would eventually need healthcare, the government could require healthy individuals to buy health insurance. While the Supreme Court ultimately upheld the individual mandate under the Taxing Power, it made clear that the Commerce Clause does not extend to noncommercial activity—even where the collective effect would have a substantial effect on commerce. “Construing the Commerce Clause to permit Congress to regulate individuals precisely because they are doing nothing would open a new and potentially vast domain to congressional authority,” wrote Chief Justice Roberts. The fact that people fail to do that which might be good for them or for society, he continued, does not sanction limitless federal authority.

A national emergency, in other words, does not turn the Commerce Clause into a blank check.

Indeed, it is precisely in the face of national emergencies that we need the Constitution’s protections most. National emergencies have prompted the federal government unconstitutionally to seize private industries and violate other fundamental civil rights.

The federal response to today’s public necessity must comply with constitutional protections. While the federal government may facilitate the use of safe and effective vaccines, the Supreme Court has already held that it may not use its Commerce Clause power to “compel citizens to act as the Government would have them act.”

Erin Morrow Hawley is Senior Counsel at Alliance Defending Freedom, Senior Legal Fellow at the Independent Women’s Law Center, and a former clerk to Chief Justice John G. Roberts.