The Exergen and Therasense Effects

This Article empirically investigates the effects of the Federal Circuit’s Exergen and Therasense decisions. It makes three main findings: First, the rate at which accused infringers won a final merits determination of inequitable conduct was 0.23 immediately preceding Exergen, dropping to 0.12 for cases between Exergen and Therasense, and then declining to 0.09 for cases post-Therasense. Second, inequitable conduct was plead in approximately 17 percent of patent cases before Exergen, 14 percent of cases between Exergen and Therasense, and 7.5 percent of cases after Therasense. Third, when courts decline to find inequitable conduct, they most often hold that proof of intent, rather than proof of materiality, is lacking. Based on these results, this Article argues that the Federal Circuit went too far in Therasense. A better formulation of inequitable conduct doctrine would be the test advocated by the dissent in Therasense, which embraced the PTO’s Rule 56 definition of materiality.