### Means plus function, determining equivalence

8/10/2007 Question asking how to determine equivalence in a means-plus-function situation. Posed in the form: which of the following are in accord with MPEP. I found MPEP 2183 to have the answers verbatim.

2183 MAKING A PRIMA FACIE CASE OF EQUIVALENCE If the examiner finds that a prior art element (A) performs the function specified in the claim, (B) is not excluded by any explicit definition provided in the specification for an equivalent, and (C) is an equivalent of the means- (or step-) plus-function limitation, the examiner should provide an explanation and rationale in the Office action as to why the prior art element is an equivalent. Factors that will support a conclusion that the prior art element is an equivalent are: (A) the prior art element performs the identical function specified in the claim in substantially the same way, and produces substantially the same results as the corresponding element disclosed in the specification. … (B) a person of ordinary skill in the art would have recognized the interchangeability of the element shown in the prior art for the corresponding element disclosed in the specification… (C) there are insubstantial differences between the prior art element and the corresponding element disclosed in the specification… (D) the prior art element is a structural equivalent of the corresponding element disclosed in the specification…

{ 9 comments… read them below or add one }

I saw this Q in the exam yesterday.

Got this one today.

Got this one today. Easy 1 point.

So was each element an answer (A through E) or something or was the answer an all of the above type??

Got this 1/18/12.

Got this on 3/17/12

Got this on 4/19/12. The answer recited 4 ways to determine equivalence and all were verbatim from MPEP so I chose answer E – all of the above.

Be on the alert: MPEP 2183 has been updated, and factor (D) (from the original post) is no longer listed in MPEP 2183. Factors (A)-(C) are still listed verbatim as in the original post (structure is still relevant to factor (C), but structural equivalent not a factor itself).

Also, be aware that the examiner only needs to show ONE of the three of these, and that this is only for a prima facie case. Applicant can rebut (MPEP 2184).

Edit: sorry, “but structural equivalent not a factor itself” should read “but structural equivalence is not a factor itself.”