In Kisor v. Wilke, the underlying case concerned a Vietnam War veteran’s quest for disability benefits. The Department of Veterans Affairs interpreted its internal rule to deny the veteran benefits going back to when he first applied. The Federal Circuit affirmed the determination using Auer deference, established by the Court in Auer v. Robbins, 519 U.S. 452 (1997), which held that courts should defer to an agency’s interpretation of its own genuinely ambiguous regulations. The veteran appealed, asking the Court to overrule Auer. In a majority opinion by Justice Kagan, the Court declined to do so under the principle of stare decisis, although it further narrowed its application. Specifically, before Auer deference should be used, the rule must be “genuinely ambiguous,” the court has exhausted all the “traditional tools” of construction to glean its meaning, the court has determined that the agency’s interpretation is “reasonable,” and the court must independently inquire whether the “character and context of the agency interpretation entitles it to controlling weight.” The Court then remanded the case for the Federal Circuit to apply those principles. Justice Gorsuch, joined by Justice Thomas and by Justices Kavanaugh and Alito in part, concurred in the judgment, but clearly was ready to discard Auer deference entirely, stating that the majority’s opinion “is more a stay of execution than a pardon,” leaving the doctrine “maimed and enfeebled—in truth, zombified.” Chief Justice Roberts, who had joined the majority opinion in part, filed a partial concurrence to state that, in his view, there was not much difference between the majority opinion and Justice Gorsuch’s opinion, and noted that this case did not concern Chevron deference (agency interpretation of statutes). Justice Kavanaugh, joined by Justice Alito, also concurred in the judgment, arguing that the application of “traditional tools” of construction should resolve most interpretation issues, and agreed that this case did not touch on the Chevron doctrine. A link to the opinion is here.