In May, the Federal Circuit decided Aspex Eyewear, Inc. v. Clariti Eyewear, Inc., 605 F.3d 1305 (Fed.Cir. 2010). The decision serves as a warning to patent and other intellectual property owners and their counsel – once one contacts a putative infringer, there must be follow through in some fashion or risk losing all rights with respect to that infringer.
The Aspex Eyewear decision affirmed (over the dissent of one Circuit judge) the dismissal on summary judgment of a patent infringement case by then-District Judge Denny Chin of the Southern District of New York based on the affirmative defense of equitable estoppel. The estoppel was based on the patent owner corresponding with the defendant and claiming infringement, and then delaying suit for over three years. Although the original demand letter was not as assertive as is often sent in such cases, and although the prejudice was relatively light, there was enough to sustain an estoppel defense, which completely barred the patent claims.