TorrentFreak has gained access to a lawsuit filed by San Francisco-based Tranz-Send Broadcasting Network against BitTorrent, Inc. claiming that uTorrent and the BitTorrent Mainline client infringes on a file-sharing related patent. The lawsuit was filed at a U.S. District Court this week and seeks monetary compensation for losses the ongoing patent infringement has caused the plaintiff.

According to the lawsuit, BitTorrent is infringing on a patent originally filed back in April 1999. “By making, operating, using and/or selling [uTorrent and BitTorrent Mainline] and or other software, BitTorrent has infringed and continues to infringe, contribute to the infringement, or induce the infringement of at least claim 1 of the ’944 patent,” the complaint reads.

Tranz-Send’s patent, “Media file distribution with adaptive transmission protocols” which was finally granted in November 2007, describes a file-sharing system consisting of a file database, a transfer client and a distribution server that doesn’t necessarily describe the way BitTorrent tosses data around between clients.

“A server/client media file distribution system is provided in which the server system is adapted to receive transmission requests from clients, status information from a network, and protocol information from each client,” the company writes in the patent abstract. “The server, based upon this information, adaptively transmits a given media file stored therein to one or more clients using the optimal transmission speed and/or network protocol based on the network status information and protocol information.”

In addition to BitTorrent, Inc., the lawsuit is also going after Kontiki Inc. on similar grounds. Unlike BitTorrent which is used by millions of file-sharers worldwide, Kontiki’s clientele consists of businesses that use the company’s media content delivery system – a hybrid of P2P transfers and central servers – to stream and distribute video. This software also allegedly infringes on Tranz-Send’s patent.

As TorrentFreak points out, if BitTorrent is found guilty of patent infringement, the company could be forced to pay royalties for each download made by its more than 100 million users since the P2P protocol went live. This could drastically impact the company’s operations and possibly spill over to other BitTorrent software companies and third-parties who use BitTorrent to distribute their legitimate software and media.

Additionally, a negative outcome could have a huge impact on the RIAA and MPAA’s current war with BitTorrent users, a long-sought victory if a guilty verdict is indeed ruled on favor of the plaintiff.