Grokster and StreamCast (Grokster) (defendants) distributed free software that allowed users to share electronic files with each other, including copyrighted materials such as songs, without permission. In distributing the software, Grokster promoted the software’s ability to allow users to download copyrighted works for free and made no effort to limit the infringement that was taking place. Metro-Goldwyn-Mayer Studios (MGM) (plaintiff), a group of copyright holders, sued Grokster for copyright infringement. The district court granted summary judgment in favor of Grokster and the court of appeals affirmed. The Supreme Court granted certiorari.