The U.S. Supreme Court has blocked the Biden administration’s Covid-19 vaccine-or-test mandate for large businesses, striking down an emergency temporary standard (ETS) from the Occupational Safety and Health Administration (OSHA) that had technically been in effect since Monday.

The court’s 6-3 decision, handed down Thursday, concluded the Biden administration overreached when it tried to force all businesses with more than 100 employees to require their workers to be vaccinated or submit to weekly Covid-19 tests. While OSHA does have the authority to regulate “work-related dangers,” contracting Covid-19 is not a risk specific to the workplace, the court’s conservative majority ruled.

The decision overturned a U.S. Court of Appeals ruling in December that lifted a temporary stay on the ETS, which OSHA first issued in November. The agency had updated its guidance and set new compliance deadlines of Jan. 10 for companies to implement a vaccine policy and Feb. 9 to comply with testing requirements for unvaccinated employees.

With Thursday’s ruling, businesses are once again on their own to decide whether to require their employees be vaccinated as a condition of employment.

“Although Covid-19 is a risk that occurs in many workplaces, it is not an occupational hazard in most. Covid-19 can and does spread at home, in schools, during sporting events, and everywhere else that people gather. That kind of universal risk is no different from the day-to-day dangers that all face from crime, air pollution, or any number of communicable diseases,” the decision said. “Permitting OSHA to regulate the hazards of daily life—simply because most Americans have jobs and face those same risks while on the clock—would significantly expand OSHA’s regulatory authority without clear congressional authorization.”

The decision went on to say OSHA might still be able to regulate Covid-19 in the workplace under certain conditions, like in a laboratory that studies live Covid-19 viruses or in cramped or crowded spaces where the risk of contracting the virus is greater.

“But the danger present in such workplaces differs in both degree and kind from the everyday risk of contracting Covid-19 that all face,” the decision read. “OSHA’s indiscriminate approach fails to account for this crucial distinction—between occupational risk and risk more generally—and accordingly the mandate takes on the character of a general public health measure, rather than an ‘occupational safety or health standard.’”

It is conceivable the Biden administration could reconfigure its vaccine-or-test mandate to apply to a narrower subset of workplaces, but its effectiveness would be dulled the longer such a rule took to be put into effect. This OSHA rule had the advantage of already being in place, albeit for just a few days.

“I am disappointed that the Supreme Court has chosen to block common-sense life-saving requirements for employees at large businesses that were grounded squarely in both science and the law,” said President Joe Biden in a statement. “… [I]t is now up to states and individual employers to determine whether to make their workplaces as safe as possible for employees and whether their businesses will be safe for consumers during this pandemic by requiring employees to take the simple and effective step of getting vaccinated.”

The Supreme Court, in a separate 5-4 decision, approved a vaccine mandate for healthcare workers whose employers receive Medicare or Medicaid payments. While there is room for workers who receive religious exemptions to sidestep the mandate, there is no testing provision for unvaccinated employees under the plan approved by the court.

The court ruled facilities which provide medical care paid for at least in part with federal dollars—including “hospitals, nursing homes, ambulatory surgical centers, hospices, rehabilitation facilities, and more”—have a responsibility to ensure their employees are not passing Covid-19 on to their patients.

As a condition of receiving federal dollars, these workplaces pledge to “maintain and enforce an ‘infection prevention and control program designed … to help prevent the development and transmission of communicable diseases and infections,’” the decision said, quoting a regulation promulgated by the Department of Health and Human Services. Large numbers of unvaccinated healthcare workers might also discourage some patients from seeking medical care, the decision said.

In the case of the vaccine mandate for healthcare workers, the court said Congress “has authorized the Secretary (of Health and Human Services) to impose conditions on the receipt of Medicaid and Medicare funds that ‘the Secretary finds necessary in the interest of the health and safety of individuals who are furnished services.’” A vaccine mandate for healthcare workers falls within that authority, the court ruled.

“After all, ensuring that providers take steps to avoid transmitting a dangerous virus to their patients is consistent with the fundamental principle of the medical profession: first, do no harm,” the court said. “It would be the ‘very opposite of efficient and effective administration for a facility that is supposed to make people well to make them sick with Covid–19.’”

“Today’s decision by the Supreme Court to uphold the requirement for healthcare workers will save lives,” said Biden. “… We will enforce it.”