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September 17, 2019 Articles

Supreme Court Spares but Limits Auer Deference

Courts will be less likely to defer to agencies' regulatory interpretations.

By Douglas Hastings and Brendan J. Anderson

In Kisor v. Wilkie, the U.S. Supreme Court significantly restricted the doctrine of Auer deference. 139 S. Ct. 2400 (2019). Under Auer (or Seminole Rock) deference, courts defer to an administrative agency’s interpretation of its own regulation when that regulation is ambiguous and the agency’s interpretation is reasonable. The split decision in Kisor leaves the doctrine intact but establishes a number of limitations to its application.

The decision is likely to impact future environmental litigation as courts will be less likely to defer to agencies’ regulatory interpretations. Agencies may respond by taking additional steps to fit their interpretations of environmental regulations within the limited scope of Auer deference recognized in Kisor


Kisor arose when James Kisor was denied retrospective benefits from the Department of Veterans Affairs for post-traumatic stress disorder. On appeal, the U.S. Court of Appeals for the Federal Circuit ruled against Kisor, deferring to the agency’s interpretation of the applicable regulation. Kisor then petitioned for a writ of certiorari, requesting that the Supreme Court reconsider Auer deference.

The Decision

Justice Kagan delivered the judgment of the court, which retained but limited Auer deference and reversed the Federal Circuit’s decision. Justices Breyer, Ginsburg, and Sotomayor joined the majority, and Chief Justice Roberts joined in part. All nine of the justices agreed with the reversal of the Federal Circuit’s decision, but Justices Gorsuch, Thomas, Alito, and Kavanaugh would have overruled Auer.

A majority of the justices voted to maintain Auer deference for stare decisis reasons. The majority found that the length of time that the doctrine had existed, the number of cases and regulations that it affected, and Congress’s inaction all weighed strongly against overturning the precedent. Kagan’s plurality also highlighted historical and policy rationales for maintaining Auer deference, but that portion of the opinion was not joined by Roberts.

Importantly for lower courts, a majority also joined the section of the opinion describing multiple limitations to Auer deference application. The majority emphasized that courts should conduct an inquiry into whether deferring to an agency is appropriate in a particular context, rather than deferring mechanically. In engaging in this inquiry, a court must determine at a minimum that (1) the regulation is in fact ambiguous using ordinary methods of construction, (2) the proffered agency interpretation is reasonable, (3) the interpretation is based on the agency’s specific expertise, (4) the interpretation is the agency’s “authoritative” interpretation, and (5) the interpretation is well reasoned and supported. Id. at 2406.

Because of the extent of the limitations recognized by the majority, both Roberts and Kavanaugh reasoned in their separate opinions that deference under Auer going forward will not be particularly strong in practice. In their view, Auer deference is not significantly different from Skidmore deference, which applies to other agency materials only to the extent that the agency’s interpretation has the power to persuade. Tellingly, Skidmore deference is the doctrine that the four anti-Auer justices believed should apply to agency regulatory interpretations.


While Auer deference survives, Kisor is likely to cabin its application. The limitations on Auer deference identified in the majority opinion will likely cause courts to more frequently reject agencies’ claims that their interpretation of a regulation is entitled to deference. In the environmental and energy context, where agencies like the Environmental Protection Agency, the Department of Interior, and the Federal Energy Regulatory Commission often interpret regulations through statements or documents that can be somewhat informal, courts may be particularly likely to question whether an agency’s regulatory interpretation is authoritative. Moreover, because the majority instructed courts to conduct a more rigorous inquiry before deferring and emphasized that its list of considerations was nonexclusive, lower courts could potentially find additional reasons not to defer to an agency’s regulatory interpretation. Kisor could even result in lower courts revisiting some agency interpretations to which they had previously deferred.

Kisor is also likely to change the behavior of agencies in interpreting regulations. In particular, agencies may take steps to ensure that their interpretations are considered authoritative, such as memorializing them through more formal procedures or clarifying that the interpretations are made by agency officials with sufficient authority regarding the topic. Agencies may also make efforts to further explain their decisions, both to help demonstrate that their interpretations are well reasoned and to clarify that the interpretations are based on the agency’s specific expertise.

Future Application

It will be interesting to see how Kisor is applied by lower courts and how both environmental agencies and litigants like environmental groups and industry stakeholders react to this shift in the level of deference given to agency regulatory interpretations.    

Douglas Hastings is an associate and Brendan J. Anderson is a summer associate at Morgan, Lewis and Bockius LLP in Washington, D.C. 

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