The creator of Captain America can invoke the termination provisions of the Copyright Act of 1976, the 2nd U.S. Circuit Court of Appeals has ruled. Deciding a case of first impression, the court found that the comic creator's settlement with Marvel Characters Inc., in which he acknowledged he devised the character Captain America while working for hire, doesn't prevent him from terminating the company's copyright under the act.
2nd Circuit Revives Attempt to End Comic Copyright
New York Law Journal
November 12, 2002