The case of Ethicon Inc. v. United States Surgical Corp. has caused some comment on the conclusion that the court reached in a situation where two persons initially collaborate but after a falling out a patent application is filed naming only one of them as inventor. The first issue before the court was whether or not the collaborator (a Mr. Choi) who was not named as an inventor should have been named as a joint inventor. The claims to be considered were written in "means plus function form". The Federal Circuit held that the contributor of any disclosed means of a means plus function claim element is a joint inventor to that claim, unless the one asserting sole inventorship can show that the contribution of that means was simply a reduction to practice of the sole inventor's broader concept.

In this case it found that Mr. Choi was therefore a joint inventor of two claims out of a total of fifty five claims in the patent under consideration. Under U.S. law, the basic presumption is that the invention belongs to the inventor rather than his employer even if the invention was conceived and/or reduced to practice during the course of the inventor's employment. This presumption may, however, be displaced if the inventor is under some form of obligation to assign his or her rights to another such as his or her employer. In the present case there was no such agreement. Therefore Mr. Choi had rights as a joint owner. According to 35 USC 262 in the absence of an agreement to the contrary, each joint owner of a patent may make, use and sell the patented invention without the permission of or the need to account to the other joint owners. A majority of the Federal Circuit held that this rule applied in the present case so that the co-inventor of a single claim is in the absence of having assigned his or her rights to someone else, the co-owner of the entire patent. Thus a license granted under the entire patent by Mr. Choi had the effect of preventing the other inventor from suing Mr. Choi's licensee for infringement even on claims to which Mr. Choi had made no contribution.

Judge Newman dissented from the majority, pointing out that in 1984 the rules on joint inventorship had been liberalized to remove the prior requirement that those named as joint inventors had to have made a contribution to every claim. It was only as a result of this change that Mr. Choi was entitled to be named as a joint inventor at all. This being the case, the court should in her view have returned to a consideration of the bases for shared ownership, which in her view is based on shared invention so that it is improper to give a contributor to a minor portion of an invention a full share in the originator's patent.