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After 17 Years in Court, Plaintiff in Festo Fails to Prove Infringement

Seventeen years after it was first filed and following two trips to the U.S. Supreme Court, the patent infringement suit filed by Festo Corp. against the SMC Corp. may be nearing an end, as a federal judge has ruled that the plaintiff failed to prove patent infringement.

"We are very pleased with the decision," said Arthur Neustadt, a partner at Oblon, Spivak, McClelland, Maier & Neustadt in Alexandria, Va., and the lead counsel for SMC.

Festo has not yet made a decision whether to appeal, Neustadt added.

The case began in 1988 when Festo sued SMC and Shoketsu Kinzoku Kogyo Kabushiki Co. Ltd. for infringing two patents relating to magnetically coupled rodless cylinders.

The technology is used for pneumatically controlling movement. It has several manufacturing and commercial uses, such as opening and closing subway doors and operating the Thunder Mountain ride at Disney World.

During the prosecution of the patents in the U.S. Trademark and Patent Office in 1981, Festo made certain amendments to the patent claims in response to objections made by the patent examiner.

The amendments added new limitations to the patents: that the inventions contain a pair of sealing rings and that the outer shell of the device, called the sleeve, be magnetizable.

SMC's allegedly infringing device was similar but used a single sealing ring and a non-magnetizable sleeve.

When Festo sued SMC for infringement, SMC contended that Festo had narrowed its claims in order to obtain the patents and thus had "surrendered" the features it had excluded in the course of amending the claims.

The lawsuit twice made its way to the Supreme Court, testing the scope of the doctrine of equivalents and the related doctrine of prosecution history estoppel.

The doctrine of equivalents is intended to prevent potential infringers from evading a patent by making insubstantial changes in the elements of a device so that the infringing device does not literally infringe a patent but still does the same thing in the same way as the patented device. The doctrine of equivalents recognizes that the scope of a patent is not limited to its literal terms but may encompass equivalents of the claims described.

Prosecution history estoppel means that a patentee cannot give up certain elements of a patent claim in order to obtain the patent, then claim that a rival is infringing its patent because its device makes use of elements equivalent to those that were given up. The presumption is that the patent holder has surrendered those elements.

In this case, the equivalent elements that Festo was presumed to have surrendered when it obtained its patents in 1981 were the single sealing ring and the non-magnetized sleeve used in SMC's device.

After its last trip to the Supreme Court, the case was remanded to the U.S. Court of Appeals for the Federal Circuit, which in turn remanded it to the U.S. District Court for the District of Massachusetts.

On remand, the District Court was left to determine whether Festo could rebut the presumption that it surrendered the single sealing ring and non-magnetizable sleeve by establishing that those claims would have been unforeseeable to one of ordinary skill in the art at the time the amendments were made to the patents.

Judge Patti B. Saris held a two-day bench trial during which Festo presented expert testimony on mechanical engineering and physics.

SMC introduced no expert testimony but relied on statements made by Festo's experts during earlier proceedings and on cross-examination of Festo's witnesses during the bench trial.

Following the testimony, Judge Saris concluded that prosecution history estoppel barred Festo from proving infringement under the doctrine of equivalents.

"Because both the single sealing ring and non-magnetizable sleeve were foreseeable to a person of ordinary skill in the art at the time of the 1981 amendments, Festo is unable to rebut the presumption of surrender of these two elements," Judge Saris said.

"Essentially, the judge said that Festo did not present any evidence to show why, if it wanted broader protection, it did not explain that to the PTO. Since the equivalents were not claimed, they were surrendered," Neustadt said.

If, in fact, Festo does not appeal, then this 17-year trip through the courts has reached its final destination.