Vicarious infringement is a legal cause of action in the United States where a person or entity indirectly and illegally uses another person or entity's copyright. More specifically, vicarious infringement occurs when an agent of a principle infringes on a person's copyright regardless of whether the principle is aware of the copyright infringement.
For example, let's say that a record label such a Virgin Records has a copyright on one of its artist's music. Because there is a copyright on this music, no person or entity is legally allowed to use this music without the express consent of Virgin Records. Furthermore, Virgin Records will unlikely give consent without monetary compensation. So, if an up-and-coming movie producer of Warner Brothers chooses to use a song in the introduction to their movie that is copyrighted by Virgin Records, without express consent, then not only has the up-and-coming movie producer committed copyright infringement, but Warner Brothers has also committed vicarious infringement.