The plaintiff, Robert Jacobsen, is the holder of a copyright for a model train software program that he makes available for free public download under the terms of an "open source" copyright license. Jacobsen brought a copyright infringement action against a defendant who allegedly used the code without following the terms of the license. Overruling a decision by the federal district court, the U.S. Court of Appeals for the Federal Circuit allowed Jacobsen's copyright infringement claims to proceed, declaring that "copyright holders who engage in open source licensing have the right to control the modification and distribution of copyrighted material." The court found that the defendants modified and distributed Jacobsen's code "without copyright notices and a tracking of modifications from the original computer files," violating license terms that are enforceable as copyright conditions.
According to Reuters, "[o]pen-source software makers share the source code of their computer programs, allowing users to help change or improve their software and redistribute it. It is a collaborative approach to software development, unlike the proprietary approach by companies like Microsoft Corp, which generally keep software code secret."