Together with the better-known Chevron deference rule, the doctrine articulated in Auer v. Robbins two decades ago—which makes reasonable administrative constructions of ambiguous administrative rules binding on courts in most circumstances—has become a focal point for concerns about the expanding administrative state. Auer deference, even more than Chevron deference, enlarges administrative authority in ways that are at odds with basic constitutional structures and due process requirements. Objections to Auer have provided cogent reasons for why courts should not grant deference to administrative interpretations merely because an agency’s rule is unclear. The most commonly voiced objections, however, do not explain why Congress should be d...