How does ex parte reexamination differ from inter partes review?

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.

Ex parte reexamination and inter partes review are two distinct procedures for reviewing patent validity. The key differences include:

• Participation: In ex parte reexamination, as described in MPEP 2209, the process is primarily between the patent owner and the USPTO. Third-party requesters have limited involvement after filing the request. In contrast, inter partes review allows ongoing participation by the challenger.
• Scope: Ex parte reexamination is based on patents and printed publications only, while inter partes review can consider a broader range of prior art.
• Timing: Ex parte reexamination can be requested at any time during the enforceability of a patent, whereas inter partes review has specific timing restrictions.
• Standard of Review: Ex parte reexamination uses a lower threshold for initiating the review compared to inter partes review.

These differences make ex parte reexamination a distinct and valuable tool in the patent review process.