Adult film company Malibu Media has sometimes been called a "porn troll," or "copyright troll," because it has sued hundreds of people for allegedly illegal downloads of pornographic movies that it owns. Malibu is believed to have filed over 1,000 such lawsuits.

Last week, a federal judge in Florida threw one of those Malibu lawsuits out of court with some remarkable legal reasoning. Just two months after Malibu filed its case, US District Judge Ursula Ungaro tossed the lawsuit Malibu filed against the user at IP address 174.61.81.171. Ungaro said that there's no proof Malibu is even in the right venue, since "[t]here is nothing that links the IP address location to the identity of the person actually downloading and viewing Plaintiff's videos and establishing whether that person lives in this district."

Malibu argued that its investigator used geolocation technology that "has always been 100 percent accurate when traced to the Southern District of Florida." It's unlikely to have come from a public Internet point like a coffee shop, given that some of the alleged infringement occurred around 5:00am (EDT), noted Malibu lawyer Keith Lipscomb. "By directing its lawsuits at IP addresses from Comcast Cable, Plaintiff knows that almost always the IP address will trace to a residential address."

Clearly, those arguments weren't good enough for Ungaro, who has dismissed and closed the case. The judicial ruling was first noted over the weekend by Fight Copyright Trolls, a blog that monitors legal action around Malibu as well as other "copyright trolls" such as the now-defunct Prenda Law.

Ungaro has insisted that Malibu justify two other lawsuits against users identified only by IP addresses.

Finding that an IP address isn't enough to get specific Internet users embroiled in a copyright suit isn't a totally new concept. A New York judge made such a ruling in a case called K-Beech v. John Does in 2012. However, that was a shotgun-style lawsuit against dozens of BitTorrent users, several of whom hired defense counsel. Also, the judge simply ruled that the case must be re-filed against specific users; he didn't throw out the case on venue grounds as Ungaro has done here.

By contrast, the Malibu Media case was thrown out quickly, without either Comcast or the user behind the IP address expending any resources. Ungaro issued her order to show cause to Malibu before they were allowed to send a subpoena to Comcast. If other judges adopt such reasoning, it could put a major dent in the copyright trolling business model.

Malibu's lawyers were sanctioned by a Wisconsin judge in September. In that case, the judge took issue with Malibu's practice of attaching lists of lewd movie titles not owned by Malibu to its complaints. Such exhibits were "calculated principally to harass defendants," wrote US District Judge William Conley.