Overargument Leads to Prosecution History Estoppel

Terlep v. The Brinkmann Corp., et al. (Fed. Cir., August 16, 2005) "provides another good example of the need for careful focusing of arguments to the Patent Examiner to points actually needed to establish patentability," writes Professor Hal Wegner:

Patentee Terlep claimed a combination that originally include a plastic
tubular "holder" - which during prosecution was amended to a "clear plastic
tubular holder": The "clear" feature was unnecessary to establish
patentability; wherefore, the patentee argued infringement under the doctrine of
equivalents against an accused embodiment that did not have a "clear" holder.
Because of overargument of patentability keyed to this unnecessary feature, the
court denied waiver of the Festo prosecution history estoppel bar.

In fact, Terlep argued to the Federal Circuit that the equivalent in question was tangential to the purpose of the amendment. However, Judge Linn was not persuaded:

The primary consideration in determining when an amendment bears only a tangential relation to the equivalent in question is "whether the reason for the amendment is peripheral, or not directly relevant, to the alleged equivalent." Insituform Techs., Inc. v. Cat Constr., Inc., 385 F.3d 1360, 1370 (Fed. Cir. 2004) (citing Festo Corp. v. Sheketsu Kinzoku Kogyo Kabushiki Co., Ltd., 344 F.3d 1359, 1365 (Fed. Cir. 2003) (en banc)). Terlep asserts that the prosecution history shows that the addition of the term "clear" was merely to describe the plastic used for the claimed "plastic holder," and thus the addition of that term is not directly relevant to the accused equivalent. However, as discussed supra, Terlep amended claim 1 and argued patentability based on the diffusion characteristics of prior art LED devices and the absence of diffusion in the clear plastic tubular holder of the claimed invention. Thus, it cannot be said that the reason for adding "clear" was tangential to the accused equivalents, which are holders that are ribbed and diffuse light. See Festo, 344 F.3d at 1369 (noting that "the inquiry into whether a patentee can rebut the Festo presumption under the ‘tangantial’ criterion focuses on the patentee’s objectively apparent reason for the narrowing amendment"). Thus, Terlep has failed to rebut the Festo presumption, and we affirm the district court's grant of summary judgment of non-infringement under the doctrine of equivalents as a matter of law.