Monsoon is accused of using open source BusyBox, a set of tools and utilities frequently included in embedded Linux products. BusyBox is issued under the GPLv2, and Monsoon has used it without making the code in which it's embedded freely available to other developers, as required by the GPL, the suit says.

The GPL was originated by Richard Stallman in 1989 to reverse the commonly accepted terms of copyright. That is, GPL users had a right to all the code issued under the GPL and could produce whatever they wished with it, provided any added code was also issued under the GPL and made freely available.

The Software Freedom Law Center was founded by Eben Moglen, Columbia University law professor and former general counsel to Richard Stallman's Free Software Foundation.

Moglen advised Stallman on the wording of GPLv3, released at the end of June. Moglen resigned from the board of directors and general counsel position in April to devote more time to his Software Freedom Law Center.

Moglen filed the suit Sept. 19 against Monsoon on behalf of two principal developers of BusyBox. "We licensed BusyBox under the GPL to give users the freedom to access and modify its source code," said Erik Andersen, developer of BusyBox and a plaintiff in the suit, in a statement. If GPL users don't abide by the GPL's terms, "we have no choice but to ask our attorneys to go to court to force them to do so.

Monsoon produces digital video products that are embedded in major supplier's hardware, including products from Intel, Microsoft, Panasonic, Nokia, HP, Dell, Toshiba, and Siemens. They are also sold directly by retailers such as Best Buy, Fry's Electronics, and CompuUSA. A current Monsoon product available at retailers lets consumers capture a TV signal from a set top box and rebroadcast it up to 300 feet through a wireless device, the Hava. It can then be shown on any PC, paused, recorded, and replayed.

The suit charges that Monsoon Multimedia infringed the copyright provisions of the GPL by redistributing BusyBox in its products without making the changes to the code and the code in which it appears available to other developers.

"If we don't ensure these licenses are respected, then we will not be able to achieve their goal," said Moglen in a statement.

The suit was filed in U.S. District Court in Manhatten and will be heard by Senior District Judge John Sprizzo. It asks that an injunction be issued against Monsoon and seeks damages and litigation expenses for Erik Andersen and co-developer Rob Landley.

Moglen chose a high profile piece of open source software to file a suit over. BusyBox is well known among open source code developers and the original version was authored by Bruce Perens, an early leader of the Debian Linux project.

GPL enforcement suits have been filed overseas but no previous GPL enforcement suit has been filed previously in the U.S.