In what may be the first action of its kind in the U.S., the Software Freedom Law Center has filed a lawsuit to enforce an open-source license.

The SFLC filed the suit on Wednesday in the United States District Court for the Southern District of New York against Monsoon Multimedia, on behalf of the developers of BusyBox, Erik Andersen and Rob Landley. The suit charges Monsoon with using BusyBox under the GNU General Public License version 2 but failing to publish its source code. Under the terms of the license, distributors of software that uses the licensed software must make their source code available. Failing to do so is considered copyright infringement.

BusyBox, members of the public and the SFLC legal team notified Monsoon of its responsibilities, but Monsoon has not yet published the code, said Dan Ravicher, legal director at SFLC. While it's relatively common for licensees to neglect to share their code, parties typically work through the issue without having to go to court, he said.

This case is a last resort after Monsoon failed to rectify the situation, he said. The suit is necessary because from a legal perspective, copyright owners can start to lose rights if they don't act to protect them, he said.

BusyBox is a lightweight set of Unix utilities used in embedded systems. Monsoon develops digital video products, including a Slingbox-like device that enables remote TV viewing.

If BusyBox ultimately prevails in the case, under copyright law the company is entitled to damages, an injunction prohibiting continued infringement and court costs, Ravicher said.

He believes this is the first case filed in the US in order to enforce an open-source license.

The GPL Violations Project is a group that actively pursues license violators and has brought at least one case to court in Germany. Earlier this year, one of the project's team members publicly revealed violations that Cisco Systems made in its phone previously called the iPhone. Cisco subsequently corrected the problem.

Monsoon did not reply to a request for comment.