Although patent infringement proceedings in the United States often begin as civil actions filed in federal district courts, many of these disputes are ultimately resolved elsewhere. Most commonly, these include administrative trials before the Patent Trial and Appeal Board (PTAB), the tribunal arm of the U.S. Patent and Trademark Office (USPTO).

At the PTAB, cases are heard by specialized administrative law judges (ALJs), referred to as administrative patent judges (APJs). A variety of proceedings are ultimately heard by these APJs, but inter partes review (IPR) is perhaps the most well-known—a proceeding challenging the patentability of claims that can invalidate part, or all, of a patent.