미국 특허소송에 있어서 판결의 효력 ―기판력 및 Kessler 법리에 관한 연방특허항소법원의 판결을 중심으로―

The Federal Circuit(CAFC) applies Claim Preclusion in case of claims in both suits are essentially the same, but not to activity after the date of judgment. Also CAFC made a lot of ruling about Collateral Estoppel, i.e. Issue Preclusion in consideration of patent litigation. And there is a tendency to enlarge the application of Res Judicata for judicial economy. The Kessler doctrine, which is a unique law to patent litigation, originated from the Kessler v. Eldred, 206 U.S. 285(1907). The Kessler doctrine fills the gap left by both preclusion. The Kessler doctrine protect an adjudged non-infringer and its customer from repeated legal harassment. The Federal Circuit brings the Kessler doctrine to life in Brain Life(2014), and broadens application of the Kessler doctrine by empowering customers to invoke it in SpeedTrack(2015). In SimpleAir (2018), CAFC stated that the Kessler doctrine applies only if scope of patent claims in both suits are essentially the same, but In Re PersonalWeb(2020), the Federal Circuit said non-infringement need not be actually litigated to invoke the Kessler dictrine contrary to collateral estoppel. It could be valuable and useful as a legal principle to control patent disputes against an unspecified number of consumers again.