Highfields Capital Management v. Doe [1]

Highfields Capital Management [2] sued an anonymous user of a Yahoo! forum [3] about the company Silicon Graphics, Inc. ("SGI"), of which Highfields was the largest shareholder.  Using the name "highfieldscapital," the user posted three messages allegedly suggesting that Highfields was profiting from the poor performance of SGI stock.  Highfields sued in Massachusetts federal court on claims of trademark infringement, defamation, trade libel, and breach of third-party contract.

After filing its complaint [4] in Massachusetts, Highfields sought a subpoena from the U.S. District Court for the District of Northern California in order to compel Yahoo! to turn over the identity of "highfieldscapital." Yahoo! notified the user of the subpoena, who moved to quash it.  The California court turned the motion over to a magistrate judge, who found that Highfields had failed to show sufficient cause for the subpoena to be issued.  The court agreed and quashed [5] the subpoena.

Highfields appealed the decision, but voluntarily withdrew its appeal before the appeals court ruled on it.  Highfields also withdrew [6] its case in the Massachusetts court due to its inability to serve the anonymous poster.