Do Conflicting Expert Opinions Preclude Summary Judgment In Patent Infringement Cases?

By Robert Ambrogi

It is a common litigation scenario: One side's expert says one thing while the other side's says just the opposite. But when - as in patent cases - expert opinion is so critical to the outcome, is summary judgment possible when the two experts disagree?

Summary judgment, after all, requires a judge to conclude that there is no genuine dispute as to any material fact. If the experts are at odds over whether a patent is infringed, isn't summary judgment ruled out?

In a September 21st opinion, In re Gabapentin Patent Litigation, the Federal Circuit Court of Appeals answered that very question in a case involving a pharmaceutical patent. In ruling that the district court erred when it granted summary judgment, the court shed light on how judges and lawyers should handle this scenario.

At the heart of the case was drug-maker Warner Lambert's patent covering a process for preparing a highly purified version of the compound gabapentin, the active ingredient in the epilepsy drug Neurontin. When several competing drug companies sought approval to market generic versions of Neurontin, Warner Lambert filed suit against them.

Through the Judicial Panel on Multidistrict Litigation, the various actions were consolidated in federal court in New Jersey. There, the defendants filed motions seeking summary judgment of noninfringement and invalidity.

A key disclosure of the Warner Lambert patent was that its process produced a gabapentin composition with "less than 20 ppm of an anion of a mineral acid." Finding that Warner Lambert failed to produce sufficient evidence to show that the defendants' generic products met this limitation and therefore infringed its patent, the district court granted summary judgment in favor of the defendants.

In the district court, Warner Lambert had based its opposition to summary judgment on the results of pH tests performed by its analytical expert. Those results, it argued, countered testing done by defendants' expert and created a genuine issue of material fact.

Conflicting Experts

On appeal to the Federal Circuit, Warner Lambert argued that the conflicting opinions of its expert and the defendants' expert - each based on different methods of testing - created a genuine issue of material fact and that the trial judge erred by resolving that factual dispute on summary judgment. The defendants countered that Warner Lambert's pH tests were invalid and imprecise.

The Federal Circuit sided with Warner Lambert, agreeing that the outcome of its expert's testing provided sufficient evidence to create a genuine issue of material fact as to whether the generic drugs would infringe its patent.

The court gave short shrift to the defendants' argument concerning the validity of the pH testing, finding that they had expressly excluded that argument from their original summary judgment motion. Ironically, they had excluded that argument in order to avoid factual disputes that might undermine their summary judgment motions.

As to the test's precision, the court found that even after factoring in the test's margin of error, the results showed that the defendants' drugs could fall within the 20 ppm claim limitation of Warner Lambert's patent.

"Based on the record before us, we conclude that the district court erred in granting summary judgment of noninfringement based on Warner Lambert's purported failure to meet its burden of proof," the court said. "The record shows that Warner Lambert proffered sufficient evidence to create a genuine issue of material fact regarding whether the accused products met the 20 ppm claim limitation of the '482 patent."

Having decided that summary judgment was improper, the Federal Circuit went on to review the trial court's construction of two key claims in Warner Lambert's patent, one defining "anion of a mineral acid" and another defining "adjuvant". In both cases, the circuit court affirmed the trial court's construction.

The case is In re Gabapentin Patent Litigation, No. 2006-1572 (Sept. 21, 2007).

This article was originally published in BullsEye, a newsletter distributed by IMS Expert Services. IMS ExpertServices is the premier expert witness and litigation consultant search firm in the legal industry, focused exclusively on providing custom expert witness searches to attorneys. To read this and other legal industry BullsEye publications, please visit


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