BnetD is an open source program that lets gamers play popular Blizzard titles like Warcraft with other gamers on servers that don't belong to Blizzard's Battle.net service. Blizzard argued that the programmers who wrote BnetD violated the DMCA's anti-circumvention provisions and that the programmers also violated several parts of Blizzard's EULA, including a section on reverse engineering.Link
The Electronic Frontier Foundation (EFF), co-counsel for the defendants, argued that programming and distributing BnetD was fair use. The programmers reverse-engineered Battle.net purely to make their free product work with it, not to violate copyright.
EFF Staff Attorney Jason Schultz said, "Consumers have a right to choose where and when they want to use the products they buy. This ruling gives Blizzard the ability to force you to use their servers whether you want to or not. Copyright law was meant to promote competition and creative alternatives, not suppress them."