What is the period of enforceability for ex parte reexamination?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

The period of enforceability for ex parte reexamination is an important concept in patent law. According to MPEP 2209:

“The period of enforceability of a patent is the period during which the patent is enforceable in a court of law, which is usually the patent term plus the 6 year statute of limitations for bringing an infringement action.”

This means that ex parte reexamination can be requested not only during the patent’s term but also for an additional 6 years after its expiration. This extended period allows for continued scrutiny of patents even after they have technically expired.