Federal courts can ill afford to ignore, assume, or improvise a pervasively important administrative power that the Patent Office exercises regularly and effectively: technology classification. This agency-court asymmetry has persisted for decades but has now become unmanageably problematic for two related reasons. First, Supreme Court guidance, patent reform legislation, and academic commentary have all broadly rejected long-standing patent exceptionalism in administrative law, while making the Patent Office a major substitute for federal courts in resolving patent disputes. Still, patent doctrine has been slow to correct, particularly in judicial deference to agency action. Second, criticisms of the patent system are highly technology-specific, and so are the reforms that have been enacted and continue to be proposed. Thus, classifying inventions is more necessary than ever, and the institutional competence to do so rests almost entirely in the Patent Office, but courts remain inattentive to the agency’s taxonomic choices. The impact of this judicial inattention is profound. Every major doctrine in patent law relies on these initial technology classifications, and competing classification methods are at the heart of the empirical research that is driving debates over patent litigation and patent quality. To remedy this problem, courts should expressly take account of Patent Office classifications and defer to those classifications unless they are arbitrary and capricious. Such deference would take necessary account of important institutional traits of the Patent Office and would give overdue respect to the administrative law principles that properly govern the patent system.