What is the relationship between 37 CFR 1.131 and interference proceedings?

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.

37 CFR 1.131 and interference proceedings are mutually exclusive procedures. As stated in the MPEP:

“Interference practice operates to the exclusion of ex parte practice under 37 CFR 1.131 which permits an inventor to show an actual date of invention prior to the effective date of a reference or activity applied under pre-AIA 35 U.S.C. 102 or 103, as long as the reference is not a statutory bar under pre-AIA 35 U.S.C. 102(b) or a U.S. patent application publication claiming the same patentable invention.”

In other words, during an interference proceeding, an inventor cannot use a 37 CFR 1.131 affidavit to antedate a reference that is subject to the interference. The interference process takes precedence in determining priority of invention.