A Practice Note on the first sale doctrine under trademark law and the doctrine's exceptions. This Note addresses the lawful resale of genuine trademarked goods under the first sale doctrine, the circumstances where defendants typically invoke the doctrine as a defense to infringement claims, and the exceptions to the doctrine that render a defendant's seemingly genuine goods non-genuine and infringing, such as when there are material differences between the parties' goods and when the defendant bypasses the plaintiff's quality control measures.