Ex Parte Reexamination
Ex parte reexamination is a USPTO proceeding to challenge the validity of one or more claims of a patent. A request for ex parte reexamination can be filed at any time during the enforceability of a patent. A request for ex parte reexamination can be filed by either the patent owner or a third party. The request must identify a substantial new question of patentability based on a patent or printed publication.
Ex parte reexamination differs significantly from post grant review (PGR) and inter partes review (IPR) in that ex parte reexamination very closely resembles ordinary patent prosecution rather than a trial proceeding. Most importantly, a third-party requester is not permitted to participate in an ex parte reexamination. Further, there is no discovery in an ex parte reexamination. However, unlike PGR and IPR, a third-party ex parte reexamination requester is permitted to remain anonymous.