On September 20, 2007, the Software Freedom Law Center (SFLC), on behalf of the BusyBox project developers, filed a lawsuit in the US District Court for the Southern District of New York against Monsoon Multimedia, Inc. BusyBox is a widely used suite of Unix utilities bundled into a single executable, licensed under gpl-v2. Monsoon Multimedia had included BusyBox in a consumer electronics device without complying with the GPL's requirements to provide source code and license notices.
The lawsuit was the first in the United States to seek judicial enforcement of the GPL's copyleft conditions. While the GPL had been in existence since release-of-gpl-v1 in 1989 and release-of-gpl-v2 in 1991, its enforceability had been established primarily through settlements rather than court judgments. Defendants who were approached about GPL non-compliance had generally come into compliance rather than face litigation. This meant the legal status of the GPL was technically untested — a vulnerability that stallman and eben-moglen had long recognized.
The case settled quickly, with Monsoon Multimedia agreeing to comply with the GPL's conditions, provide source code to its customers, and cooperate with ongoing compliance. While the settlement meant there was no binding court precedent, the willingness to file and the defendant's rapid capitulation established that the GPL's enforcement mechanism was credible and that the gpl-copyleft-mechanism's conditions could be backed by litigation.
The SFLC, founded by eben-moglen in 2005, used this case and subsequent BusyBox actions against other defendants to build a body of enforcement practice. bradley-kuhn, who later co-founded the software-freedom-conservancy, was centrally involved in this enforcement work. The software-freedom-conservancy subsequently developed its own enforcement program, most notably around the BusyBox project, and later the Corresponding Source Verification Program.
The case matters for stallman's project because copyleft is only as strong as its enforcement. The free-software-definition is embodied in the GPL's legal text, but legal text means nothing if it cannot be enforced. The 2007 lawsuit was the proof of concept that copyleft was a real legal instrument, not merely a philosophical statement, vindicating the legal architecture that stallman conceived and eben-moglen refined in gpl-v3.