Board of Patent Appeals: The Problem with Using Functional Language in Claims – Florida Patent Lawyer Blog

Written by: Mark Terry

Yesterday’s Board of Patent Appeals and Interferences (BPAI) decision in Ex Parte Zurcher highlighted the problems associated with using functional language in claims, especially when claiming an apparatus. I, a Patent Lawyer in Miami, have written about this before in my article about intended use claim language.

The Ex Parte Zurcher case involved an electrical-type socket invention. The claim element at issue included functional language. The Examiner asserted a prior art reference that included structure that performed the same function as described in Appellant’s functional language. I.e., the Examiner found the claimed functional language inherent in the prior art reference. The ensuing arguments can be separated in three types:

Argument #1

First, the Appellant argued that the structure of the prior art was not the same as the structure disclosed by Appellant in the specification. Nice try, but even a 1st year knows that’s a losing argument. You should only be arguing about what’s in the claims, not the specification. The Board disagreed with the Appellant and found:

“The fact that the structure of the prior art is structurally different from the structure of the ‘disclosed embodiment’ Appellant described in the Specification and depicts in the Figures is of little moment. The name of the game is the claim. In re Hiniker Co., 150 F.3d 1362, 1369 (Fed.Cir.1998).”

Argument #2

Second, the Appellant argued that one of ordinary skill in the art must recognize that the prior art’s structure would be capable of performing the functional language of Appellant’s claim. The Board disagreed once more and stated:

“There is no such requirement. See Schering Corp. v. Geneva Pharms., Inc., 339 F.3d 1373, 1377 (Fed. Cir. 2003) (“Continental Can does not stand for the proposition that an inherent feature of a prior art reference must be perceived as such by a person of ordinary skill in the art before the critical date.”); In re Imeprazole Patent Litig., v. Andrx Pharms, Inc., 483 F.3d 1364, 1373 (Fed. Cir. 2007) (recognition in the prior art is not necessary when the claimed characteristic or function is inherently present in the prior art).”

Argument #3

Lastly, the Board identified the central issue as one of simply determining whether the prior art structure performed the same function as the functional claim language. Period. The Board decided :

“[a] patent applicant is free to recite features of an apparatus either structurally or functionally.” In re Schreiber, 128 F.3d 1473, 1478 (Fed. Cir. 1997). “Yet, choosing to define an element functionally, i.e., but what it does, carries with it a risk.” Id. “Where the Patent Office has reason to believe that a functional limitation asserted to be critical for establishing novelty in the claimed subject matter may, in fact, be an inherent characteristic of the prior art, it possesses the authority to require the applicant to prove that the subject matter shown to be in the prior art does not possess the characteristic relied on. Id., (quoting In re Swinehart, 439 F.2d 210, 213 (CCPA 1971) and further citing In re Hallman, 655 F.2d 212, 215 (CCPA 1981); In re Ludtke, 441 F.2d 660, 663-64 (CCPA 1971).)”

Lessons Learned: If you use functional language in your claim, the Examiner must only find structure in a prior art reference that performs the same function. The Examiner is NOT required to find the same structure you disclose in your specification and the Examiner is NOT required to prove that a POSITA would know the prior art structure can perform the function at issue. Additionally, the Examiner does NOT have to show that the intended use of the prior art structure is the same as that of the Appellant. Again, the Examiner must only show the prior art structure can perform the functional claim language.

In conclusion, beware of functional claim language, especially when claiming an apparatus. It is more desirable to use structural claim language, which would require an Examiner to find the same structure in the prior art – often a more difficult task.


We are board-certified intellectual property attorneys, inventors, and engineers that help small-size inventors, entrepreneurs, and businesses register and protect patents, copyrights, and trademarks so you can profit from them faster.

Call Now: 786.443.7720