The law doesn’t just prevent actions, it compels them, too. That’s why Blizzard shut down the fan-run World of Warcraft server called Nostalrius.

After fan outcry, Blizzard explained in depth why they ordered the cease and desist.

“Failure to protect against intellectual property infringement would damage Blizzard’s rights,” wrote World of Warcraft‘s executive producer, J. Allen Brack in a post on the forums for the game. Anything using the intellectual property associated with the game without permission is subject to this. There isn’t, Brack says, “a clear legal path to protect Blizzard’s IP and grant an operating license to a pirate server.”

In short, if they don’t protect their property, they won’t be able to continue to do so. Not defending your property can forfeit your right to defend it.

Blizzard understands the demand for what fans call “vanilla” servers, which are servers running the original version of the now 12-year-old game. Brack says his team looked into developing something like this, but for Blizzard to do it would, interestingly, be more difficult than it is for the pirate servers. Pirate servers can break, go offline, be compromised, or whatever else, and no one is really responsible. If Blizzard runs a classic server, they become responsible for all of that, essentially supporting two very different versions of the game, which is down to 5.5 million subscribers as of last fall, far from its height of 12 million.

It’s a frustrating situation caused not so much by Blizzard as by the confusing mess that is United States copyright law.

For active fans of the game, the next expansion, World of Warcraft: Legion, is due out at the end of August, adding a Demon Hunter class and new areas.