The transfer of rights in a patent generally fall into two categories: an assignment and a license. The transfer is usually accomplished by an agreement.
Whether the agreement at issue is an assignment or a license matters because generally an assignee can sue for infringement alone, while a licensee of less than substantially all of the patent rights cannot sue for infringement alone without the patent owner.
A patent grants the owner certain rights, such as the right to exclude others from making, using, offering for sale, or selling the invention throughout the United States or importing the invention into the United States. 35 U.S.C. § 154(a)(1)
Usually, an assignment transfers all of the rights* of one party in a patent to the recipient (the assignee). Vaupel Textilmaschinen KG v. Meccanica Euro Italia S.P.A., 944 F.2d 870, 875 (Fed. Cir. 1991); 35 USC 261. Also, a transfer of substantially all of the patent rights can be considered an assignment for the purposes of standing to sue for infringement. A transfer of less than substantially all of the rights, is a mere license. It is the content and legal effect of the agreement that determines whether it is an assignment or license, not its title.
In the Vaupel case, the court found the agreement at issue there transferred substantially all of the rights in the patent, where the seller retained the following rights: “1) a veto right on sublicensing by Vaupel; 2) the right to obtain patents on the invention in other countries; 3) a reversionary right to the patent in the event of bankruptcy or termination of production by Vaupel; and 4) a right to receive infringement damages.” Therefore, despite the seller retaining these rights, the agreement at issue was considered an assignment.
In contrast, in Sicom Sys. v. Agilent Techs., Inc., 427 F.3d 971, 978-979 (Fed. Cir. 2005), Canada licensed the patent at issue to plaintiff Sicom. The court found the license did not transfer substantially all of the rights, where Canada reserved the right to use the patented technology itself, to veto Sicom’s reassignment of its rights, and to sue for non-commercial infringement. Canada also retained legal title to the patent.
The line between a transfer of substantially all of the rights and less than substantially all of the rights is gray. Ignoring this issue and simplifying it, an assignment usually transfers everything (including legal title) whereas a license grants less than all of the rights and reserves rights to the person or entity granting the license.
*The Supreme Court has also said that the transfer of an undivided portion or share of a patent can also be an assignment, but then assignor and assignee must act together to sue for infringement. Waterman v. Mackenzie, 138 U.S. 252 (1891).