A federal court last week ruled that copyright owners can only sue multiple peer-to-peer users if all of the defendants participated in the same infringement scheme.

In recent years, copyright owners have sued people who have shared their movies, songs, and other content via peer-to-peer networks such as BitTorrent. The copyright owners use proprietary software to obtain the IP addresses of BitTorrent users who are downloading and sharing the copyright holders’ content. Rather than filing individual lawsuits against each user, the copyright owners often name dozens of alleged John Doe infringers in the same complaint. After filing the complaint, the copyright owners typically issue subpoenas to the customers’ Internet service providers to determine the identities of the John Doe defendants.

Although courts have generally approved the subpoenas for the identities of John Doe defendants in copyright infringement cases, plaintiffs are encountering a new obstacle, as illustrated in the September 27 opinion by Judge John Z. Lee, a district judge for the U.S. District Court for the Northern District of Illinois.

In this case, Malibu Media filed two complaints: the first against 68 John Doe defendants nationwide who had allegedly used BitTorrent to download and disseminate a movie entitled “Happy Couple;” the second complaint alleges that 42 defendants infringed Malibu Media’s copyright in a movie entitled “Backstage.”

Federal civil procedure rules only allow plaintiffs to name multiple defendants in a single lawsuit if the claims are made “with respect to or arising out of the same transaction, occurrence, or series of transactions or occurrences,” and where there is at least one “question of law or fact common to all defendants.” Malibu Media claims that because all of the defendants copied the same copyrighted work with the same unique hash identifier, the joint lawsuit was proper.

Judge Lee rejected this argument. Following the logic of other district courts that have recently confronted similar issues, Judge Lee held that joinder would be proper only if all of the defendants were part of the same “swarm” that shared the file on BitTorrent at the same time. Judge Lee wrote that the fact that the complaints allege that the defendants copied the same files “demonstrates only that they all downloaded the same piece of a file at some point during the swarm’s existence. It does not establish that the Defendants were all part of the swarm when they shared parts of the copyrighted work with one another.” Accordingly, Judge Lee granted the motion to sever all but one defendant from each of the lawsuits.

Although copyright owners will be able to continue to file lawsuits to obtain the identities of alleged infringers, Judge Lee’s opinion indicates that they often will be required to file individual suits, which are far more costly than a single lawsuit against numerous defendants.