Many regulatory agencies have authority to promptly protect against grave dangers—so long as the danger is not too grave, according to recent Supreme Court jurisprudence. Agencies are often delegated emergency authority to address risks rapidly, though temporarily, to protect the public from novel, virulent risks. If the risk not only affects the public’s health but also is of major political or economic significance, however, the U.S. Supreme Court has expressed a desire to limit this authority based on the major questions doctrine. Essentially, the circumstances in which agency action would be most beneficial are also the ones in which agency action is most in danger of being blocked. This Article argues that the application of the major questions doctrine to emerging risks not only lacks legal justification but poses significant physical peril. The Article presents novel empirical evidence undermining the conjectures used by the U.S. Supreme Court to usurp OSHA’s authority and provides guidance to agencies in how to survive elevated scrutiny in future emergency measures.The Court’s application of the major questions doctrine in Nat’l Fed’n of Indep. Bus. v. Dep’t of Lab, Occupational Safety and Health Administration conflicts with regulatory agencies’ statutory obligation to protect the public from grave health dangers. During the COVID-19 pandemic, the Occupational Safety and Health Agency (OSHA) exercised its emergency authority in promulgating the emergency temporary standard (ETS) requiring large employers to have their workers vaccinated or masked/tested. Based on the evidence summarized in its ETS, OSHA concluded that COVID-19 posed a grave danger to workplaces with significant social contact. In refusing to uphold the ETS, the Supreme Court narrowly defined the scope of risk OSHA could regulate, represented irreversible protections as inferior to reversible ones, and imposed inconsistent burdens relative to those applied to other agencies’ emergency measures. These unpersuasive distinctions mask the Supreme Court’s fixation on narrowing the scope of regulation, justified implicitly or explicitly through the major questions doctrine. This Article presents novel empirical evidence undermining the Court’s conjectures and supporting OSHA’s finding that workplaces engaging in social behaviors were at greater risk from COVID-19. OSHA’s claim that the hazards were not confined to health care industries alone was borne out by the pattern of occupational illnesses that emerged during the pandemic. Using publicly available data on occupational illness rates by industry, we find that there was a widespread increase in occupational illnesses after the advent of COVID-19. The evidence demonstrates that the largest percent increases in illness rates were not confined to one or two narrow industries, as the U.S. Supreme Court hypothesized. There were substantial linkages between occupational illnesses and occupational characteristics that prompted OSHA’s concerns, such as assisting and caring for others, establishing and maintaining interpersonal relationships, and performing for or working directly with the public. Occupational illness rates increased at a greater rate from 2019 to 2020 in industries where there is substantial social interaction. In light of this evidence, the Supreme Court’s limiting of COVID-19 risk to a few industries impeded OSHA’s attempt to mount an emergency response to a major national threat. This Article argues that this substitution of inexpert conjecture for evidence is not only legally unjustified but deadly in the context of emerging risks. The Court’s second-guessing of OSHA’s evidence, based on nothing but an implicit desire to restrict regulatory authority, not only exposed workers to greater health risks but also created a dangerous precedent for how regulatory agencies can respond to future emergencies. This Article cautions against imposing a heightened evidentiary burden to justify emergency action for novel risks, as such delay will exact a high physical price when the relevant information may not exist. Moreover, focusing on narrowing the scope of regulation will result in under-protection in the future, as populations and risks become more difficult to silo. When faced with future crises meriting an emergency response, agencies will be reluctant to undertake preventive measures, anticipating that their initiative will be overturned if the hazard is particularly consequential. The precedent established by the Supreme Court’s decision will cost lives by limiting agencies’ ability to act quickly when grave threats emerge. This Article discusses strategies for agencies in future crises, suggesting that our methodology can be used to bolster the evidentiary case for emergency action