SCO v. IBM
The 2003 lawsuit in which SCO Group claimed Linux was built on stolen Unix code — a case that ran for eighteen years and never produced the code.
In March 2003 SCO Group sued IBM for a billion dollars, later raised to five, for putting Unix System V code into Linux. It sent warning letters to 1,500 companies, sold "Linux licenses" and sued AutoZone and DaimlerChrysler. Microsoft and Sun bought Unix licenses from SCO that same year, which few people took for a coincidence.
The case collapsed on another front: in 2007 the court in SCO v. Novell ruled that Novell had never sold the Unix copyrights, and a jury confirmed it in 2010. SCO went bankrupt, but the IBM suit lived on inside the bankruptcy estate until IBM settled in 2021 for $14.25 million. The Groklaw blog tracked every filing and made it one of the most scrutinised cases in software history.