What issues can be considered in ex parte reexamination ordered under 35 U.S.C. 304?

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 ordered under 35 U.S.C. 304 is limited to considerations of prior art patents and printed publications. The MPEP states:

“Rejections will not be based on matters other than patents or printed publications, such as public use or sale, inventorship, 35 U.S.C. 101, conduct issues, etc.”

However, certain ancillary matters may be considered, such as double patenting, correction of inventorship, and claiming foreign priority or domestic benefit. Issues not based on prior art patents or printed publications raised in a prior Office or court decision should be noted but not considered in the reexamination.