Better known as Blizzard v. bnetd, this case curbs the development of new computer programs that interoperate with existing ones when faced with potential infringements under the Digital Millennium Copyright Act (DMCA). Blizzard, producer of popular computer games such as “Diablo,” “StarCraft,” and “WarCraft,” hosts an online-gaming service called “Battle.net” designed as the exclusive way for owners of Blizzard games to play each other via the Internet. A purchaser of a Blizzard game is presented with an End User License Agreement (EULA) and Terms of Use (TOU), both of which prohibits reverse engineering, that must be agreed to before the software may be installed, as well as a unique CD-Key that serves to authenticate the software with Battle.net.

Bnetd was an open source software package that emulated the Battle.net service and allowed users to play Blizzard games on their own user-created servers instead of having to connect to Battle.net. While players must supply a CD-Key to connect to bnetd, its validity is not authenticated as on Battle.net, thus allowing potentially pirated copies to be connected. Blizzard filed suit in the District Court for the Eastern District of Missouri against the three developers of Bnetd, as well as an ISP (Internet Gateway) that hosted a bnetd server, for violating the terms prohibiting reverse engineering in its games’ EULA and TOU, and the anti-circumvention and anti-trafficking provisions of the DMCA. The district court granted summary judgment in favor of Blizzard, finding the EULA and TOU contracts to be enforceable, thus vitiating any “fair use” defense, and that defendants violated the provisions under the DMCA.

On appeal, the Eighth Circuit affirmed all judgments in favor of Blizzard. The Eighth Circuit rejected the defendant’s argument that federal copyright law, which permits reverse engineering, preempts state contract law in which the EULA and TOU was grounded. The Court held that by agreeing to the EULA and TOU, the developers expressly relinquished their rights to reverse engineer. Other circuits, notably the Ninth Circuit, have declined to enforce similar shrink-wrap license agreements, suggesting that Blizzard’s choice in selecting the district court in Missouri rather than its home state of California was a tactical decision to keep the case out of the Ninth Circuit on appeal.

Regarding the DMCA violations, the Eighth Circuit held that bnetd violated the anti-circumvention and anti-trafficking provisions in allowing unauthorized copies of Blizzard games to be played on its servers, thus circumventing Battle.net’s authentication measures. Furthermore, the interoperability exception under the DMCA that protects individuals using circumventing technology for the sole purpose of trying to achieve interoperability of computer programs through reverse engineering did not apply to bnetd as the circumvention in this case constituted infringement.

Editor’s note: While Blizzard won the lawsuit, the distribution of bnetd derivatives and similar server emulators has not ceased. See, e.g., PvPGN and BNCS. Also, the Electronic Frontier Foundation maintains an archive of materials relating to this case.
Thanks to Han Xu for his assistance with the preparation of this post.