Since 1945, the Supreme Court has given binding respect to a federal agency’s interpretation of its own regulation unless the agency’s construal is incorrect. This principle is commonly known as either Auer or Seminole Rock deference, named after the two cases most often associated with the doctrine’s canonical formulation—that an agency’s regulatory construction is of “controlling weight unless it is plainly erroneous or inconsistent with the regulation.” Although this strong form of deference has existed for more than seventy years, it has become the subject of an intense academic debate only in the last two decades and the polemics have created practical consequences. In 2013, for example, Chief Justice John Roberts announced that the Supreme Court has “some interest in reconsidering” the doctrine. In the current 115th Congress, the House of Representatives has passed legislation that would replace Auer deference with de novo review and the Senate is considering a bipartisan companion bill that would replace Auer deference with non-binding judicial respect.