Unclaimed Functions Cannot Be Imported Into A Means-Plus-Function Limitation

In Applied Medical Resources Corp. v. United States Surgical Corp . (No. 05-1314; May 15, 2006), a divided panel of the Federal Circuit vacates a district court's grant of summary judgment of non-infringement. In so doing, the panel concludes the district court misapplied the "function-way-result" test in analyzing a means-plus-function limitation of a claimed "trocar," a surgical device that provides a channel through the abdominal cavity through which instruments can be inserted during laparoscopic surgery. With respect to this limitation, U.S. Surgical had successfully argued to the district court that the gimbal of the accused trocar was not equivalent to the "ring-levers-teeth" structure disclosed in the patent. According to the panel, a genuine issue of material fact exists as to whether this is true.

In its analysis, the majority panel concluded that the district court improperly imported unclaimed functions into the means-plus-function limitation. In particular, the panel concludes the district court, in its infringement analysis, improperly determined the way in which the disclosed structure performs the previously-defined function . The panel further notes that "the way in which the structure performs the properly-defined function … should not be influenced by the manner in which the structure performs other, extraneous functions."

In a dissent, Judge Dyk disagrees, arguing that the district court did not improperly redefine the function. Judge Dyk asserts that the district court simply concluded that the two devices did not perform the agreed function in the same way. Further, Judge Dyk asserts that the majority's approach expands the scope of claims under 35 U.S.C. § 112, sixth paragraph, by failing to enforce the requirement that the patentee show that the accused device performs the required function in substantially the same way as the patented device.