The Occupational Safety and Health Administration adopted an emergency temporary standard requiring many employers with at least one hundred employees to impose a COVID-19 vaccination policy or require regular testing and masking. The National Federation of Independent Business and other applicants asked the Supreme Court to stay the rule while litigation continued. The Court held that the applicants were likely to succeed in showing that OSHA lacked authority to impose the broad mandate. The Occupational Safety and Health Act authorizes workplace safety standards addressing occupational dangers, but the statute did not clearly empower OSHA to regulate the ordinary public-health risks of daily life on this scale. The Court stayed the rule, while explaining that OSHA could regulate occupation-specific dangers and that healthcare-facility requirements were governed by a separate case. Justice Breyer, joined by Justices Sotomayor and Kagan, dissented, concluding that the statutory authority and record supported OSHA’s emergency response.