What factors are considered when deciding equivalence in means-plus-function claims?

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.

When determining equivalence in means-plus-function claims, examiners consider several factors. According to MPEP 2184, the primary considerations are:

1. Identical function: “Unless an element performs the identical function specified in the claim, it cannot be an equivalent for the purposes of 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph.”
2. Indicia of equivalence: While there’s no absolute test, several indicia can support a conclusion of equivalence or nonequivalence. These indicia are detailed in MPEP 2183.

Examiners weigh these factors along with any evidence or arguments presented by the applicant to determine whether the applicant has met the burden of proving nonequivalence.