This chapter analyses cases of copyright infringement in the online environment. It begins by analysing some early cases regarding file-sharing technologies, including A&M Records, Inc. v Napster, Inc., MGM Studios, Inc. v Grokster, Ltd, and Sweden v Neij et al. (The Pirate Bay case). It assesses new techniques for fighting illegal file-sharing, such as blocking access to websites offering file-sharing technology or indexes with a focus on the operation of s.97A website blocking orders. It examines the Supreme Court decision in Cartier International v British Sky Broadcasting and its application in the Nintendo cases Nintendo Co Ltd v Sky UK Ltd and Nintendo Co Ltd v British Telecommunications Plc. Finally, it describes the slightly controversial process known as speculative invoicing and examines the recent case of Mircom International v Virgin Media.