Joint ownership is created when a copyrightable work is created by the efforts of two or more persons. Unless there is a different agreement of the parties, each owner has undivided rights in the work and is permitted to assign his or her rights to a third party. However, there can be no assignment of the whole work without the consent of all owners. In addition, joint owners of a work have the right to use or license the use of the work subject to a duty to account to the other co-owners for any profit.
In determining whether a contributor to a work is actually a coauthor of a joint work, the courts will look to see if the contributor exercised control over the work, whether there was an intent by the parties to be coauthors, and whether the work was successful due to both contributions.
Joint works are distinguished from derivative works. Derivative works include separate and independent works of authorship rather than inseparable or interdependent work. Joint ownership of a derivative work alone does not create a “joint work.”