Robert Jacobson, the developer behind the open source Java Model Railroad Interface (JMRI) project, finally prevailed in a long-running open source software license enforcement lawsuit against Matthew Katzer, the owner of a company that sells commercial model train software.

Katzer initially threatened Jacobson and JMRI with a patent infringement lawsuit in 2005, and demanded hundreds of thousands of dollars in licensing fees. Upon investigating Katzer's claims, Jacobson was surprised to discover that Katzer had misappropriated significant amounts of JMRI code, using it without attribution in a commercial software package. Jacobson retaliated against Katzer's patent suit by filing a copyright infringement suit.

The case has attracted considerable attention within the open source software community because it has broad ramifications for open source license legality. A federal appeals court that heard the case in 2008 ruled that violating the terms of an open source software license constitutes copyright infringement, not just breach of contract. The distinction is important because the legal remedies for copyright infringement are generally stronger.

After the 2008 ruling, the case was passed back to the district court so that the appropriate remedy could be determined. In a summary judgement issued in December, the district court ruled that Jacobson is entitled to collect monetary damages from Katzer. The judgment also declared that Katzer's removal of attribution and copyright information from the JMRI code constituted a violation of the Digital Millennium Copyright Act.

Although the ruling won't set a broad precedent due to the fact that it emerged from a district court, it's still a significant victory for open source software licensing enforcement. The threat of having to pay monetary damages will give software companies a big incentive to refrain from abusing or misappropriating open source software code. In response to the ruling, Katzer finally agreed to settle with Jacobson last week. The conflict, which originally started five years ago, has reached an end.