Ethicon v. United States Surgical Corp. 135 F.3d 1456 (Fed. Cir. 1998) Yoon was a doctor who was working on technologies related to endoscopes. He worked with a guy named Choi for a while, but eventually they stopped working together. Yoon applied for and received a patent on a some kind of doo-dad called a 'trocar'. He listed himself as the sole inventor of the invention, despite the fact that Choi had helped. Yoon licensed the trocar to Ethicon. Yoon didn't bother to tell Choi about the patent. There is a presumption that the person whose name is on the patent is the true inventor. Despite the fact that Choi's handwriting was on the documents Yoon submitted to get the patent. Later, Ethicon sued USSC for infringement. USSC found Choi and sued to get Choi's name listed on the patent as an co-inventor. USSC signed a licensing deal with Choi, and argued that if Choi was the co-inventor, then USSC couldn't be sued for infringement. The Trial Court found for USSC. Ethicon appealed.  The Trial Court found that Choi was the co-inventor of several of the claims in Yoon's patent. See 35 U.S.C. §116, which provides guidance on joint inventions. The Appellate Court affirmed. The Appellate Court found that joint inventors need not each make the same amount of contributions to the patent. However, to be a joint inventor you can't merely assist, you have to be able to prove your contribution to the conception of the claims (by clear and convincing evidence). To be a co-inventor you have to do more than just help with basic principles or explain what the state of the art is, or just reduce the invention to practice. You have to actually come up with some ideas (aka conception). The Court looked at the evidence presented in the Trial Court and found that it showed by clear and convincing evidence that Choi met the definition of a co-inventor. The Court found that even though Choi only contributed to some of the claims in the patent, as a co-inventor, he gets the right to license the entire patent. Choi only argued that he was responsible for 2 of the 55 claims in the patent. Yet, because he was a co-inventor, he gets the rights to the entire patent, even the 53 claims he admits he had nothing to do with. Prior to 1984, inventorship was ground for patent invalidity, and if there was a situation like this, Yoon's patent would have been declared invalid. Interestingly, as a co-inventor Choi had the right to license the technology and keep 100% of the money he earned from USSC. Even though Yoon was a co-owner he got nothing. Conversely, under copyright law joint authors can independently license their joint work, but they have to share the profits among all the authors.