In two per curiam opinions released Thursday afternoon, the Supreme Court released long-awaited guidance on two vaccine mandates issued by federal agencies.

The first, National Federation of Independent Business v. Department of Labor, involved the Emergency Temporary Standard (ETS) issued by the Occupational Safety and Health Administration (OSHA), which would have required employers with more than 100 employees to enact policies requiring employees to either be vaccinated or undergo weekly testing for COVID-19. The Court found in favor of the petitioners and stayed enforcement of the rule. The opinion issued the stay on the conclusion that such a rule goes grossly beyond OSHA’s authority to set workplace safety standards. The Court noted the ETS attempts to implement broad public health measures, rather than standards limited to the workplace.

A concurrence by Justices Gorsuch, Thomas, and Alito discussed the constitutional authority of the federal government, reasoning that the power to respond to the pandemic “rests with the States and Congress, not OSHA.” Justices Breyer, Sotomayor, and Kagan dissented on the basis that the holding usurped OSHA’s power as the federal agency responsible for workplace safety, opining that it was “acting well within the scope of [its] authority, to protect American workers from grave danger.”

Because of the holding, enforcement of the OSHA ETS, which began on January 10, is now stayed. The Court will rule on the substance of the rule at a later date. Given the Court’s reasoning in support of the stay, any future guidance by OSHA will not likely address mandatory vaccination, as the Court took specific issue with the vaccination requirement and how it expands beyond OSHA’s “occupational” authority. The agency still may be able to require other measures, such as testing, distancing, and masking in the workplace.

The second, Biden v. Missouri, tackled the Department of Health and Human Services’ vaccine mandate for healthcare workers, which applies to employees of qualifying entities receiving Medicare and Medicaid funding (the Omnibus Rule). The Court sided with the Government, finding that the Secretary of Health and Human Services had long-established authority to “help prevent the development and transmission of communicable diseases” in healthcare environments; ultimately, the rule fits “neatly within” the agency’s statutory authority, and the Court found “no grounds for limiting the exercise of authorities the agency has long been recognized to have.”

Justices Thomas, Alito, Gorsuch, and Barrett dissented, finding that the statutory provisions cited did not make a “strong showing” that the rule was necessary, parsing through language to find that the agency’s authority was not broad enough to justify such a mandate.

Enforcement of the Omnibus Rule was on hold while challenges pended in half of U.S. states. It is not yet clear whether those states will be on the same timeline as the other 25, where the current rule is that employees must have at least one dose of a COVID-19 vaccine by January 27, 2022, and the second by February 28, 2022. However, qualifying healthcare entities in all 50 states must now prepare to comply.