What are the limitations of 37 CFR 1.131(a) affidavits in patent applications?

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.

While 37 CFR 1.131(a) affidavits are useful for antedating certain prior art references, they have several important limitations:

1. Statutory Bars: As stated in MPEP 715.01, “An affidavit or declaration under 37 CFR 1.131(a) is not appropriate where the reference is a statutory bar under pre-AIA 35 U.S.C. 102(b).”
2. AIA Applications: These affidavits are not applicable to applications subject to the first-inventor-to-file provisions of the AIA.
3. Scope: They can only be used to overcome certain types of prior art under pre-AIA 35 U.S.C. 102(a) or (e).
4. Timing: They are typically filed before final rejection and may not be entered after final rejection without good and sufficient reason.
5. Evidence Required: The affidavit must provide sufficient evidence of prior invention, which can be challenging to produce.

It’s important to consult with a patent attorney to determine if a 37 CFR 1.131(a) affidavit is appropriate and sufficient for your specific case.