Defendants use laches, an ancient equitable doctrine, as an affirmative defense in patent infringement suits. Laches applies when a patent owner, referred to as the patentee, unreasonably delays in filing suit against the alleged infringing defendant. Defendants in patent infringement suits invoke laches by showing not only that the patentee unreasonably and inexcusably delayed filing, but that the delay caused “material prejudice” to the defendant. While the laches defense is infrequently raised, it is helpful when eliminating damages awarded to the patentee. Laches remains a powerful tool for defendants by completely barring recovery for infringement before suit.
This Note examines the laches defense in recent Federal Circuit and Supreme Court copyright and patent infringement cases, and evaluates whether the Supreme Court should uphold the use of laches in patent infringement cases.