17.21 Secondary Liability-Contributory Infringement-Elements and Burden of Proof is the legal doctrine that holds an individual or entity liable for copyright infringement if they have knowingly and materially contributed to the infringing activities of another. The elements and burden of proof for contributory infringement are set out in the U.S. Copyright Act. The elements of contributory copyright infringement include: 1. Knowledge — The accused must have knowledge of the infringing activity; 2. Material Contribution — The accused must have materially contributed to the infringing activity, either by providing assistance or resources; 3. Causation — The accused's contribution must have been a cause of the infringement; and 4. Intent — The accused must have intended to facilitate the infringing activity. The burden of proof for contributory copyright infringement is on the plaintiff to show that the accused had knowledge of the infringing activity and intended to facilitate it. Additionally, the plaintiff must show that the accused's contribution was a cause of the infringement. There are two types of contributory copyright infringement: direct and vicarious. Direct contributory copyright infringement occurs when an individual or entity knowingly and materially contributes to the infringing activity of another. Vicarious copyright infringement occurs when an individual or entity has the right and ability to control the infringing activity of another, and benefits financially from the infringing activity.