Steuben Foods, Inc. v. Shibuya Hoppmann Corp

Authored by: Jeremy J. Gustrowsky

A recent appellate decision has clarified the boundaries of patent infringement and the doctrine of equivalents in the context of aseptic food packaging technology. Steuben Foods, Inc. accused Shibuya Hoppmann Corporation and others of infringing three patents—U.S. Patent Nos. 6,209,591, 6,536,188, and 6,702,985—related to high-speed, sterile bottling systems. After a jury found in favor of Steuben on validity and infringement, the district court overturned the verdict, granting judgment as a matter of law (JMOL) for noninfringement on all patents. Steuben appealed, and the Federal Circuit has now reversed much of that decision.

The appellate court reinstated the jury’s finding of infringement for the ‘591 and ‘188 patents. For the ‘591 patent, the court held that there was enough evidence for the jury to reject the so-called “reverse doctrine of equivalents” defense, which argues that an accused product, while literally covered by the patent, operates on a fundamentally different principle. The court found that Steuben’s expert provided credible testimony supporting infringement, and the jury was entitled to rely on that evidence. Similarly, for the ‘188 patent, the court determined that the accused product’s structures were sufficiently equivalent to the claimed means-plus-function limitations, again supporting the jury’s verdict.

However, the court affirmed the district court’s ruling of noninfringement for the ‘985 patent. The key issue was the claim requirement that sterilant be “intermittently added” to a conduit. The parties had agreed that “intermittently added” means “added in a non-continuous manner.” Because the accused system added sterilant continuously, the court found that treating this as equivalent would improperly erase a clear claim limitation—something the doctrine of equivalents does not allow.

The Federal Circuit also vacated the district court’s conditional grant of a new trial on damages and invalidity, finding the lower court had not provided adequate reasoning. The case was sent back for further proceedings on those issues. This decision underscores the importance of both the evidence presented at trial and the precise language of patent claims, especially when applying the doctrine of equivalents.