Davidson v. Jung
A 2005 US case in which the volunteer developers of a replacement Battle.net server lost on both breach of contract and the DMCA.
bnetd was an open-source server that spoke the same protocol as Blizzard's Battle.net, letting players run StarCraft and Diablo on their own networks. Its developers, among them Ross Combs, Rob Crittenden and Tim Jung, had worked out the protocol by studying the client and its traffic. Blizzard's parent Davidson & Associates sued, and the Electronic Frontier Foundation took up the defence.
The Eighth Circuit sided with Blizzard in 2005. The click-through agreement banned reverse engineering and was binding. The DMCA's interoperability exemption did not help either, because bnetd never checked CD keys and so let pirated copies play online. The project shut down in the US but carried on as the fork PvPGN, hosted somewhere more forgiving.