Use of “mechanism” in claim without more may result in means-plus-function interpretationDecember 18, 2008

In a decision Monday, the Federal Circuit affirmed a district court's claim construction and related judgment of noninfringement. The decision focused on the issue of claim construction in means plus function claims. The critical limitation used the term "mechanism" without any additional structural elements, and as a result the district court construed it to be a means-plus-function claim. The Federal Circuit affirmed, noting in the past it had held limitations with the term "mechanism" without additional modifiers to be means-plus-function limitations. Because it was undisputed the accused device did not have the corresponding structure in the specification or its structural equivalent, the court affirmed the district court's grant of summary judgment.

More detail of Welker Bearing Co. v. PHD, Inc. after the jump.

Welker Bearing Co. (Welker) received U.S. Patent number 6,786,478 ("the '478 patent") in September 2004. Based on the reasoning for allowance by the USPTO, Welker filed a continuation application with broader claims, eventually resulting in U.S. Patent number 6,913,254 (the '254 patent), which issued July, 2005. While both the '478 and '254 patents shared the same specification, claim 1 of the '478 patent explicitly required a rotational mechanism, a limitation not present in the '254 patent. A comparison of the two claims is below:

PHD developed two products, the Clamp I and Clamp II devices, which Welker accused of infringing its patents. The Clamp I device featured a rotational mechanism, as in the limitation of the earlier '478 patent. Welkor contacted PHD shortly after the '478 patent issued, and PHD ceased production of the Clamp I device after failing to reach a licensing agreement with Welkor. PHD then developed the Clamp II device, which lacked the rotational mechanism.

After the '254 patent issued, Welkor sued PHD for infringement of its '478 patent based on the Clamp I device, and infringement of its '254 patent based on the Clamp II device. The case for infringement of the '478 patent was easily resolved as there was no evidence presented by Welker that PHD had offered for sale or used the product after the '478 patent issued.

The district court considered claim construction of claim 1 of the '254 patent. The district court characterized the term "a mechanism for moving said finger" to be a means-plus-function limitation. While the claim did not include the word "means," the Federal Circuit has interpreted the term "mechanism" to be sufficiently generic (when not otherwise modified) so as to be interpreted as a means-plus-function limitation. The lack of additional text to indicate structure instead of the vague term "mechanism" led the court to look to the specification for corresponding structure. The only structure described in the specification that the court was able to find to describe the "mechanism for moving said finger" included the limitation of rotational movement. Therefore, because the Clamp II product did not include this limitation, it could not infringe the '254 patent, and the district court granted summary judgment of noninfringement. Welker appealed.

The Federal Circuit affirmed. The court first easily affirmed the finding of noninfringement of the '478 patent, noting that it was Welker's burden to prove some infringing act took place after the patent issued. Welker asserted PHD had an affirmative duty to take the product off the market, but the court rejected this contention, stating: "PHD did not have any burden to prove it retracted any putative offer for sale. Rather the burden remains with the patentee to prove infringement, not on the defendant to disprove it." Accordingly, the court affirmed the judgment of noninfringement of the '478 patent.

Turning to the '254 patent, the Federal Circuit addressed the claim construction issue. The Federal Circuit, agreeing with the district court, held the relevant limitation did not recite sufficient structure, and as a result was properly characterized as a means-plus-function claim. The court reached this conclusion, even though it made the claims of the two patents very close, if not identitcal in scope. The court provided Welker with a litany of alternatives that may have produced a different result:

The applicant for the '254 patent could have supplied structural context to claim 1 in any number of ways. If claim 1 of the '254 patent had recited, e.g., a "finger displacement mechanism," a "lateral projection/retraction mechanism," or even a "clamping finger actuator," this court could have inquired beyond the vague term "mechanism" to discern the understanding of one of skill in the art. If that artisan would have understood such language to include a structural component, this court's analysis may well have turned out differently.

As a result, the court affirmed the district court's claim construction. Under this construction, literal infringement was not possible, and the Federal Circuit therefore affirmed the judgment of noninfringement.

To read the full decision in Welker Bearing Co. v. PHD, Inc., click here.