Revisiting the troublesome sixth paragraph of 35 U.S.C. § 112, the U.S. Court of Appeals for the Federal Circuit reversed a jury verdict of infringement holding there was a lack of substantial evidence where the plaintiff had failed to provide a structural analysis of the means-plus-function limitation in a contested claim. CytoLogix Corp. v. Ventana Medical Systems, Inc., Case No. 04-1446 (Fed. Cir. Sept. 21, 2005) (Dyk, J.).
At trial, CytoLogix and Ventana had agreed, contrary to the district court’s wishes, to forego a Markman hearing and to present expert witnesses to testify before the jury regarding conflicting claim constructions. The Federal Circuit disapprovingly noted in its opinion that when experts opine on claim construction before the jury, the risk of jury confusion is high, even when the district court makes it clear that its construction controls.
After the jury returned its verdict of infringement, the district court entered a judgment for CytoLogix and an injunction against Ventana. Ventana appealed, arguing the jury verdict resulted from an erroneous claim construction provided by the court. As neither party objected to the claim construction at trial, the Federal Circuit held that the issue on appeal was limited to whether the substantial evidence supported the verdict under the court’s construction.
One of the patents-in-suit contains the claim limitation "temperature controller means for regulating electric power," which is a means-plus-function limitation under § 112 ¶ 6. As noted by the Court, in order to establish that the relevant structure in the accused device is "identical or equivalent to" the corresponding structure in the specification, the patent holder must do more than present testimony on the function of the structure.
Here, the testimony presented by CytoLogix through its expert witnesses identified a microprocessor in the accused product that they argued was the "means for converting temperature data," and, therefore, it satisfied the district court’s construction of the "temperature controller." The Federal Circuit, however, held that CytoLogix failed to compare the corresponding disclosed structure of the "temperature controller" in its patents to the structure of the accused device. Accordingly, the Federal Circuit held that CytoLogix failed to present substantial evidence of infringement of that claim and reversed the jury verdict of infringement.
Practice Note
When arguing infringement of a claim with means-plus-function limitations, conduct a structural analysis of the accused product and compare it to the structure disclosed in the specification.
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