Federal agencies in the United States hear almost twice as many cases each year as all the federal courts. But agencies routinely avoid using tools that courts rely on to efficiently resolve large groups of claims: class actions and other complex litigation procedures. As a result, across the administrative state, the number of claims languishing on agency dockets has produced crippling backlogs, arbitrary outcomes and new barriers to justice.

A handful of federal administrative programs, however, have quietly bucked this trend. The Equal Employment Opportunity Commission has created an administrative class action procedure, modeled after Rule 23 of the Federal Rules of Civil Procedure, to resolve “pattern and practice” claims of discrimination by federal employees before administrative judges. Similarly, the National Vaccine Injury Compensation Program has used “Omnibus Proceedings” resembling federal multidistrict litigation to pool common claims regarding vaccine injuries. And facing a backlog of hundreds of thousands of claims, the Office of Medicare Hearings and Appeals recently instituted a new “Statistical Sampling Initiative,” which will resolve hundreds of common medical claims at a time by statistically extrapolating the results of a few hearing outcomes.

This Article is the first to map agencies’ nascent efforts to use class actions and other complex procedures in their own hearings. Relying on unusual access to many agencies — including agency policymakers, staff and adjudicators — we take a unique look “inside” administrative tribunals that use mass adjudication in areas as diverse as employment discrimination, mass torts, and health care. In so doing, we unearth broader lessons about what aggregation procedures mean for policymaking, enforcement and adjudication. Even as some fear that collective procedures may stretch the limits of adjudication, our study supports a very different conclusion: group procedures can form an integral part of public regulation and the adjudicatory process itself.