Lawrence O. Gostin is a professor and faculty director of the O’Neill Institute for National & Global Health Law at Georgetown Law, director of the World Health Organization Collaborating Center on Public Health Law & Human Rights and author of “Global Health Security.” Dorit Rubinstein Reiss is professor at University of California, Hastings College of the Law.

The U.S. Court of Appeals for the 5th Circuit on Saturday temporarily blocked President Biden’s vaccine-or-test emergency rule for large businesses, saying it raised “grave statutory and constitutional issues.” The ruling was the opening salvo in a broad challenge to the president’s powers, likely to end up before the Supreme Court.

But critics of the emergency rule are wrong. The president is acting well within the powers that Congress has delegated to him.

Biden draws his power from the Occupational Safety and Health Act, which Congress enacted in 1970 to address a weak patchwork of state worker-safety laws. The act granted the federal government wide, but not unlimited, authority to set national workplace safety standards.

It’s true that OSHA standards are usually for traditional workplace hazards such as injuries or toxic chemicals. But OSHA has regulated infectious diseases several times, including standards for blood-borne pathogens to combat HIV and hepatitis. The fact that the coronavirus is circulating in the community does not make it less of a workplace hazard. Indoor workspaces pose a special risk because many workers remain crowded indoors for eight hours.

It’s also true that states, not the federal government, possess the constitutional power to prevent the spread of infectious diseases. But that doesn’t mean the federal government lacks public health powers. Congress authorized federal quarantine powers in 1796. And the Centers for Disease Control and Prevention has been exercising extensive power to prevent the interstate or international spread of infectious diseases since Congress enacted the Public Health Service Act of 1944.

In terms of his emergency rule, Biden isn’t acting unilaterally. Rather, he is acting under a law enacted specifically to regulate workplace safety through the Occupational Safety and Health Administration. Congress’s constitutional power to set national workplace safety standards derives from the commerce clause and isn’t controversial. Courts have upheld OSHA’s powers to regulate the workplace for half a century. The agency’s emergency rule isn’t even breaking new ground; it’s only unprecedented because of its scope.

Many point to the Supreme Court’s recent decision striking down the CDC’s eviction moratorium as evidence that Biden is overreaching. But by regulating housing, the CDC was acting at the edge of its legislative authority. Here, OSHA is acting well within what it was designed to do — setting workplace safety standards — and using traditional tools to fight infectious-disease hazards, such as vaccination, testing and masking.

Opponents also challenged the decision to issue an emergency standard, which meant OSHA didn’t have to go through the usual notice-and-comment period. The courts have blocked most of OSHA’s previous emergency standards. But the highly contagious delta variant isn’t a false or exaggerated emergency; it is a clear and present danger. More than 1,000 people are dying everyday from covid-19, including many infected in the workplace. OSHA conservatively estimated its new rule would prevent more than 6,500 deaths and 250,000 hospitalizations. A long notice-and-comment period would have cost thousands of lives. If the pandemic isn’t an emergency, it’s hard to say what would be.

OSHA has met the statutory criteria for an emergency rule: It has demonstrated a “grave” workplace danger and that the measures are necessary to prevent it. OSHA didn’t apply its rule to workers who are at reduced risk, such as remote workers or those working outdoors. This careful line-drawing should help the rule withstand scrutiny.

The rule is also necessary and proportionate because coronavirus vaccines are the single-most effective prevention of transmission, hospitalization and death available. The testing and masking edicts are evidence-based prevention tools, too. There is also an added public benefit because behavioral science research tells us that most people will choose to get the vaccine rather than undergoing regular testing and masking, and workers won’t want to bear the financial cost of testing. If a free vaccination is the easier, default choice, it will boost vaccination rates, benefiting everyone.

It’s possible the 5th Circuit’s stay of Biden’s rule will be temporary. The OSHA regulations don’t come into effect until Jan. 4, 2022 (The mask requirement takes effect Dec. 5.) But any delay could cost lives and generate uncertainty. Many businesses may stop planning for compliance until a full court ruling. The court also blocked the immediate requirement for businesses to pay for time off to vaccinate and for any adverse effects.

Take a step back to understand what opponents of Biden’s mandates are saying. They’re claiming that workers have a right to go to work without vaccinating, testing or masking. Ignoring all that we know about the rapid spread of the delta variant in crowded indoor spaces would be reckless. Congress wisely granted OSHA the power and duty to ensure that workers can safely return to their loved ones. The courts should not second-guess professional health and safety experts.