Court isn't the only route to patent invalidation. When a plaintiff sues a defendant for patent infringement, there are usually two defenses brought up: "I'm no

Court isn't the only route to patent invalidation. When a plaintiff sues a defendant for patent infringement, there are usually two defenses brought up: "I'm not infringing on your patent" and "even if I were, your patent is invalid." Prevailing on the latter defense begets invalidation. Third parties can also file ex parte or inter partes reexamination request, through which the third party can ask the USPTO to reexamine the patent to verify the patentability of the claimed subject matter. The fee for requesting an ex parte proceeding is $2520, and after filing the request, the third party no longer actively participates in the proceedings. Third parties filing an inter partes request, after paying the $8800 fee, may continue to participate in the proceedings.