On January 17, the United States Supreme Court heard more than three hours of oral argument on whether Chevron deference—the doctrine that requires courts to defer to an agency’s reasonable interpretation of an ambiguous statute—should be abandoned or modified. The argument suggests a substantial possibility that the doctrine may be modified, if not overturned entirely. Either result would put litigants in a stronger position to challenge agency action with which they disagree, although, as the oral argument made clear, the real impact is uncertain.

The oral arguments occurred in two related cases1 concerning whether a rule passed by the National Marine Fisheries Service, which required certain fisherman to bear the costs of federal monitors on their fishing boats, was permissible under a statute. Two Courts of Appeals had upheld the rule, relying on the deference doctrine first enunciated forty years ago in Chevron v. Natural Resources Defense Council.2 The Supreme Court agreed to hear both cases to decide whether Chevron should be overruled, or at least clarified to provide that no deference was proper where a statute was silent.

At the oral argument, Justices Gorsuch and Kavanaugh appeared strongly in favor of overturning Chevron, with Justice Gorsuch suggesting that “Chevron is exploited against the individual and in favor of the government,”[3] and Justice Kavanaugh stating that Chevron “ushers in shocks to the system” in a wide variety of fields whenever presidential administrations change.4

Justices Thomas and Alito seemed to question the statutory and constitutional basis for Chevron, both as a legal and practical matter. Justice Alito, for instance, was particularly troubled about the difficulty that lower courts have had in determining whether a federal statute is ambiguous, thus triggering Chevron deference. Justice Alito further questioned why the Chevron two-step process was even necessary, given that “in cases that don’t involve an agency, we never say we have exhausted all of our tools of interpretation and we just can’t figure out what this means.”5 For his part, Justice Thomas could not seem to square the rule with Section 706 of the Administrative Procedure Act (APA), which provides that reviewing courts should decide all relevant questions of law when agency action is appealed—a statutory provision that Petitioners noted was not even discussed in Chevron.

In varying degrees, these conservative justices all seemed sympathetic to the Petitioners’ concerns about consistency with the APA’s requirement that courts ultimately decide legal issues presented by agency proceedings, about separation of powers concerns raised by the doctrine, and about consistency of interpretations of federal law, which Petitioners argued was undermined by Chevron deference to agency legal interpretations.

Justices Kagan, Sotomayor, and Jackson, on the other hand, appeared strongly in favor of keeping Chevron (with perhaps enhancements to address some of the concerns raised in the argument), not only as a matter of precedent, but because in their view, it keeps judges out of important policy decisions they are not well-equipped to make. For example, Justice Kagan referenced hypothetical legislation concerning artificial intelligence, and her view that “what Congress wants, we presume, is for people who actually know about AI to decide those questions.”6 Justice Kagan cited a number of federal statutory regimes—like FDA determinations of whether a cholesterol lowering product is a drug or a dietary supplement—that she strongly suggested judges were not suited to make. Justice Jackson repeatedly returned to the theme of agency expertise, and whether judges are suited for making what she viewed as policy decisions in interpreting ambiguous statutes.

The case may ultimately come down to either Chief Justice Roberts or Justice Barrett—or both. Both justices were less open about what position they might ultimately take, and it is possible that they are searching for a way to limit and/or clarify Chevron without discarding the case entirely. For instance, the Chief Justice indicated that the Supreme Court has not cited the case in a number of years, questioning whether “we overruled it in practice even if we’ve let the – had to leave the lower courts to continue to grapple with it?”7 Justice Barrett suggested that overturning Chevron might be a shock to the legal system. But she also raised questions suggesting sympathy with the petitioners’ position. Justice Kagan seemed at times to be probing how Chevron might be tweaked in a way that might be acceptable to these justices, including engaging with the Solicitor General on her suggestion of how the Court might “clarify and articulate the limits of Chevron deference without taking the drastic step of upending decades of settled precedent.”8 The Solicitor General offered several examples of how Chevron might be modified to save deference in cases of ambiguity, but require more exhaustive analysis using traditional rules of statutory interpretation to determine whether, in fact, a statute was truly ambiguous.

Oral argument does not always signal how a particular judge will vote. Often, a justice’s questions are simply airing concerns or genuinely seeking to clear up confusion. Thus, predicting the result on the basis of questioning at argument is fraught with peril. But to the extent such tea leaves can be read, the questions and discussion at the argument signal a substantial chance that Chevron could be overruled or substantially modified. The Solicitor General, echoing language used throughout the argument, indicated this would be a “shock to the legal system,”9 but only time will tell if that is really the case. At a minimum, parties seeking to curb or modify agency action will likely be in a better position than they have been since the era of Chevron deference began.