American Hospital Association v. Bowen

HHS (defendant) issued directives and transmittals governing Peer Review Organizations without notice and comment, and the AHA (plaintiff) petitioned for rulemaking, arguing the bulk of PRO procedures were improperly issued outside the APA's formal rulemaking process; after HHS didn't respond, the AHA sued to have the directives declared invalid.

Whether procedural rules that do not substantially alter the interests of a regulated party are subject to the notice and comment requirements of the APA.