What is the burden of proof for nonequivalence in means-plus-function claims?

When a prima facie case of equivalence has been made by the examiner, the burden shifts to the applicant to prove nonequivalence. According to MPEP 2184, “Where, however, the specification is silent as to what constitutes equivalents and the examiner has made out a prima facie case of equivalence, the burden is placed upon the applicant to show that a prior art element which performs the claimed function is not an equivalent of the structure, material, or acts disclosed in the specification.”

Applicants can meet this burden by providing:

  • Teachings in the specification that particular prior art is not equivalent
  • Teachings in the prior art reference itself that may show nonequivalence
  • 37 CFR 1.132 affidavit evidence of facts tending to show nonequivalence

To learn more:

Topics: MPEP 2100 - Patentability, MPEP 2184 - Determining Whether An Applicant Has Met The Burden Of Proving Nonequivalence After A Prima Facie Case Is Made, Patent Law, Patent Procedure
Tags: Burden Of Proof, means-plus-function, Nonequivalence, Prima Facie Case