Although the open source movement has been active for more than a decade, it is only in recent months that such a copyright license actually has received the imprimatur of enforceability — from an unlikely court (the Federal Circuit) construing a perhaps unlikely license (the Java Model Railroad Interface for model train software). Open source licensing, of course, is the innovative (if controversial) tool that makes source code available to the general public on conditions (of varying severity) to guarantee continued public access to works derived from the original. Such licenses can require licensees to disclose source code and distribute derivative works royalty-free. Well-known open source licenses include the Creative Commons License, Apache License and Sun Community Source License. Perhaps best-known is the General Public License, now in its third version, which governs Linux, MySQL, and other major software products. It is perhaps also the most feared for its requirement that any source code compiled with any GPL-licensed source code be publicly disclosed upon distribution — often referred to as “infection.”

However, despite the great interest in open source licensing, there has been virtually no precedent construing or applying any of these widely used “copy-left” licenses (or indeed any open source licenses) prior to the Federal Circuit’s December decision in Jacobsen v. Katzer, 535 F.3d 1373 (Fed Cir. 2008). Although Jacobsen left many issues still to be decided (a point well demonstrated on remand), the Federal Circuit held that breach of an open source license does not merely permit a breach of contract claim, but that violating the “conditions” to the intellectual property license creates a cause of action for copyright infringement — with associated remedies. Indeed, in turning the focus from contract to infringement, the Federal Circuit remanded for the district court to reassess its denial of a preliminary injunction.