Fair use
The U.S. Supreme Court has traditionally characterized fair use as an affirmative defense, but in "Lenz v. Universal Music Corp." (2015) (the "dancing baby" case), the U.S. Court of Appeals for the Ninth Circuit concluded that fair use was not merely a defense to an infringement claim, but was an expressly authorized right, and an exception to the exclusive rights granted to the author of a creative work by copyright law: "Fair use is therefore distinct from affirmative defenses where a use infringes a copyright, but there is no liability due to a valid excuse, e.g., misuse of a copyright."