In 1984, the case Chevron v. Natural Resources Defense Council established a doctrine in which courts defer to federal agencies’ “reasonable” interpretation of an “ambiguous” statute. There is a challenge to the legitimacy of this principle. Four justices show criticism, while three justices seem inclined to keep the status quo. Two cases, Loper Bright Enterprises v. Raimondo and Relentless v. Department of Commerce, challenge if herring fishermen have to subsidize the salaries of on-board observers. Prelogar contends the National Marine Fisheries Service has the discretion to fill the “gap” left by congressional silence, while Clement and Martinez argue this violates due process, the separation of powers, and the rule of law. Kavanaugh asked Prelogar, “How would you define ambiguity?” Her response was that a judge might apply “all of the tools” of statutory interpretation and conclude that “Congress spoke to the issue.” Prelogar suggested that the justices could respond to varying understandings of ambiguity by reminding the lower courts that they are not supposed to give up on statutory interpretation just because it is difficult to choose between contending views. Overturning Chevron, she said, would be an “unwarranted shock to the legal system,” while Gorsuch et al. argued that Chevron has undermined stability by allowing agencies to overrule judicial interpretations and “flip-flop” between different readings of a statute, depending on the agenda of any given administration. Prelogar also argued that preserving Chevron would promote “stability” and “predictability,” noting that both legislators and regulators have come to rely on the assumption that agencies have broad discretion in filling gaps and resolving ambiguity. However, Gorsuch et al. argued that Chevron has undermined stability by allowing agencies to overrule judicial interpretations and “flip-flop” between different readings of a statute, depending on the agenda of any given administration. In short, while Prelogar argued that Chevron promotes uniformity by constraining judges from reading their own policy preferences into the law, Gorsuch et al. argued that it has the opposite effect. In Chevron, the court deferred to an agency interpretation that benefited regulated companies, prompting Gorsuch to assert that the doctrine tends to negatively impact the less powerful. He cited as an example the plaintiffs in Relentless and Loper Bright, who claim that the contested regulatory fees amount to about a fifth of the revenue earned by their family-owned businesses. Kagan, Sotomayor, and Jackson, amplified Prelogar’s argument that agency experts are best situated to fill in the gaps left by Congress and promote Chevron’s stability and predictability.