In a likely setback to the MPAA and RIAA's antipiracy efforts, a federal judge has ruled that an IP address alone is not enough to accuse a specific individual of illegal downloads.

An IP address only identifies the location at which any number of Internet-connected devices may be located, much that a single telephone number can be used by many telephones, Magistrate Judge Gary R. Brown of the U.S. District Court for the Eastern District of New York said in a ruling earlier this week.

"Thus, it is no more likely that the subscriber to an IP address carried out a particular computer function -- here the purported illegal downloading of a single pornographic film -- than to say an individual who pays the telephone bill made a specific telephone call," Brown said in his 26-page ruling (see below).

Brown recommended that the case, which accused unidentified defendants of illegally downloading adult movies, be dismissed because discovering the identity of the individual associated with a device was "unlikely" to reveal the identity of the true defendant.

"Most, if not all, of the IP addresses will actually reflect a wireless router or other networking device, meaning that while the ISPs will provide the name of its subscriber, the alleged infringer could be the subscriber, a member of his or her family, an employee, invitee, neighbor or interloper," Brown wrote.

The ruling comes as Voltage Pictures, the movie studio behind "The Hurt Locker," filed a new round of lawsuits against 2,500 BitTorrent users it accuses of illegally downloading the Oscar-winning film. The studio, which alleges it has lost millions of dollars in revenue, hopes to get a subpoena to reveal the alleged movie sharers' identities via their ISP addresses.

Judge Gary Brown IP Address Ruling