Summary Judgment of Noninfringement Reversed Where Defendants Challenged Only Precision, and Not Validity, of Testing Methods

Case: Warner-Lambert Co. v. Purepac Pharmaceutical Co., Case No. 2006-1572 (Fed. Cir. 9/21/07)

The One Sentence Summary: Summary judgment of noninfringement was reversed where the Federal Circuit, while affirming the district court's claim construction, rejected defendants' arguments which had focused on the precision of testing methods, rather than validity, to support findings of noninfringement.

What They Were Fighting About: The district court had granted summary judgment finding no infringement of plaintiff's patent for a process for producing an epilepsy drug. The Federal Circuit affirmed the district court's claim construction, but reversed summary judgment on infringement, finding material issues of fact as to whether defendants' products used the process claimed by Warner Lambert's patent.

Federal Circuit Holdings:

• The district court had found on summary judgment that Warner Lambert failed to meet its burden of showing defendants products used two key limitations which were part of the patent, and thus found no infringement. The Federal Circuit found genuine issues of material fact warranting reversal of that judgment
• The Federal Circuit focused on test results provided by Warner Lambert's expert, and the fact that Defendants had challenged only the precision of the testing method, not whether the test itself produced scientifically meaningful results.
• With respect to testing precision, the Federal Circuit noted that within the range of testing error, several test results showed that the sample met the claim limitation in the allegedly infringed patent, and thus these tests did not support granting summary judgment and finding no infringement.
• The Federal Circuit further rejected the argument that, because plaintiff had drafted its claim in quantitative terms (specifying "less than 20 ppm of an anion of a mineral acid"), proving infringement required a test that quantified the level of acidic chloride in the sample. The Court reasoned that the testing method used allowed an inference that the quantitative limitation was met, and defendants had waived any challenge to the validity of that test method.
• Defendants had also challenged the claim construction in arguing there was no infringement. First, the Federal Circuit agreed with the district court's construction that "anion of a mineral acid" meant "anion derived from a mineral acid," rather than any anion, because otherwise the phrase "of a mineral acid" added nothing to the claim. Second, the Federal Circuit concurred with other aspects of the claim construction, rejecting defendants' arguments.