Congress did not intend fair use to be an affirmative defense. It is clearly a right under US copyright law. The rights granted to copyright owners in section 106 are expressly “subject to” the fair use defense. The fair use section of the Act, section 107, provides expressly that fair use “is not an infringement of copyright", rather than an infringement with an affirmative defense. In Lenz v. Universal the courts say that fair use is "distinct from affirmative defenses where a use infringes a copyright, but there is no liability due to a valid excuse.” and that “fair use is ‘authorized by the law’ and a copyright holder must consider the existence of fair use before sending a takedown notification….”