The most familiar doctrine in administrative law is Chevron deference: when Congress leaves an ambiguous gap in a piece of legislation, the regulations that fill it "are given controlling weight unless they are arbitrary, capricious, or manifestly contrary to the statute." Less well known is the deference that applies to agencies' interpretations of their own regulations. This doctrine, known alternately as Auer deference or Seminole Rock deference, gives an agency's interpretation "controlling weight unless it is plainly erroneous or inconsistent with the regulation." Auer is important. For now, the doctrine still sits in Chevron's shadow, but it presents issues that, in the words of Chief Justice Roberts, go "to the heart of administrative law" and "arise as a matter of course on a regular basis."
The Uneasy Case Against Auer and Seminole Rock,
Yale L. & Pol'y Rev.
Available at: https://digitalcommons.law.yale.edu/ylpr/vol33/iss1/5