Addressing whether a failure to present evidence of doctrine of equivalents would compel a new trial in light of a district court’s post-trial modifications to its claim construction, the U.S. Court of Appeals for the Federal Circuit held that a patentee, who was on notice that the court’s pretrial claim construction contained significant ambiguities, could not claim its failure to present evidence of infringement under the doctrine of equivalents was the result of surprise at the district court’s modified claim construction. Power Mosfet Technologies, LLC v. Siemens AG, Case Nos. 03-1083, -1469, -1470, -1471 (Fed. Cir. Aug. 17, 2004) (Gajarsa, J.).
Power Mosfet Technologies (PMT) is the owner of U.S. Pat. No. 5,216,275 (the `275 patent). Directed to a semiconductor power device design in which the voltage sustaining layer (the layer that, when not conducting current, sustains a voltage between the source and drain terminals) results in a new relationship between the breakdown voltage and the on-resistance. According to the `275 patent, the new relationship allows lower on-resistance values without the same magnitude of accompanying loss in breakdown voltage found in traditional semiconductor devices.
PMT sued Siemens AG and several other marque semiconductor manufactures, alleging infringement of the `275 patent. A special master (in a Markman ruling essentially adopted by the district court) construed the disputed claim terms of the `275 patent, but as isolated terms, rather than within the context of the claims. The parties were aware that substantial ambiguities in the claim construction existed when the claims were read as a whole. Namely, the parties continued to dispute whether the claims required that specific layers of the claimed semiconductor device be in physical contact. Despite this ambiguity, PMT did not present any evidence of infringement under the doctrine of equivalents. Following the bench trial, the district court modified its claim construction to reconcile the ambiguity and adopted a claim construction that resulted in a finding of non-infringement. PMT asked for a new trial but the court refused. PMT appealed, arguing that in relying on the district court’s initial claim construction it had been precluded from presenting evidence of doctrine of equivalents.
The Federal Circuit affirmed the denial of PMT’s motion for a new trial, reasoning that all parties were aware that the special master’s claim construction as adopted by the district court was ambiguous and subject to further modification. Since there is no requirement that there be a final claim construction at the outset of the trial, PMT could not claim surprise as a basis for failing to present evidence on the doctrine of equivalents.
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