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Mitsubishi Electric Corp. v. Ampex Corp., No. 97-1502, 1999 U.S. App. LEXIS 20688, (Fed. Cir. Aug. 30, 1999).




1. Whether a reviewing court must vacate a verdict of patent invalidity where the verdict form did not specify the grounds of invalidity but the appellant did not renew its objection to a general verdict form prior to jury submission.

2. Whether testimony of experts and the inventor, supported by the inventor's report, was substantial evidence to support a jury verdict that the patents were invalid.


1. No. Although the general rule established by the Supreme Court in Maryland v. Baldwin, 112 US 490 (1884) (ruling that a general verdict cannot stand if it is based on alternative theories, one of which is erroneous or improperly submitted to the jury), is a correct principle of law, a party must preserve its objection to the form of the verdict in order to raise the issue on appeal.

2. Yes. Documentary evidence alone was sufficient to support a finding that the device was used in public and, accordingly, the patent claim for the '612 patent was invalid. Moreover, with respect to the '533 patent, there was substantial evidence to support the jury's finding that a combination of prior art references was obvious based on the conflicting testimony of expert witnesses and articles presented at trial. Therefore, the verdict of invalidity for the '533 patent was also sustained.


The Mitsubishi Electric Corporation is the owner of United States Patent No. 4,336,612 ("the '612 patent"), which details a system for correcting errors that occur during the transmission, recording, or reproduction of digital information. Mitsubishi also owns United States Patent No. 4,665,533 ("the '533 patent"), which describes a method improving the transmission of digital data by placing synchronizing codes into a stream of data. Mitsubishi filed suit against Ampex Corp. for infringement of both patents. Mitsubishi now appeals the jury verdict that the asserted claims of both patents were invalid. Both parties relied heavily on expert testimony at trial.

The verdict form submitted to the jury did not distinguish among the three asserted grounds of invalidity. Mitsubishi agued that if any of these grounds were submitted erroneously, the verdict must be vacated because it would be impossible to know if the jury reached the verdict on erroneous grounds. Mitsubishi asserted this argument with respect to both the '612 patent and the '533 patents. The Federal Circuit held that Mitsubishi did not preserve its objection to the form of the verdict for either the '612 or the '533 patents, and that therefore Mitsubishi waived its right to raise the issue on appeal.

Mitsubishi also argued a lack of substantial evidence to support the jury verdicts. The Federal Circuit rejected this argument with respect to the '612 patent and held that documentary evidence (here, an inventor's contemporaneous report) alone supported a finding of invalidity on the grounds of prior public use during a convention demonstration. The Federal Circuit also rejected this argument with respect to the '533 patent, finding that a reasonable jury could conclude, based on the competing testimony of expert witnesses and the relevant articles presented at trial, that the claim of the '533 patent would have been obvious to someone of ordinary skill in the art. Since the evidence presented by the experts was not challenged, the Court affirmed the invalidity of '533 patent.


Prepared by the liibulletin-patent Editorial Board.

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