NEW YORK – A U.S. federal appeals court has ruled that the holder of a copyright to a computer programming code made available for free public download can enforce an “open-source” copyright license to control future use of the work.

The ruling on Wednesday by the U.S. Court of Appeals for the Federal Circuit is seen as having important ramifications for the licensing of open-source software. Open-source proponents had argued that individuals who do not adhere to the conditions of an open-source license should be subject to copyright infringement claims.

The appeals court reversed a lower court ruling that had denied a preliminary injunction to plaintiff Robert Jacobsen, a hobbyist who made software used for model trains available through free downloads.

Jacobsen had brought copyright infringement claims against developers of commercial software products, contending they did not follow terms of the software's license. The lower court had ruled that copyright claims did not apply, but that Jacobsen could pursue breach of contract claims.

The distinction is important because the potential remedies under federal copyright law are much stronger than under contract law, said Jacobsen's lawyer, Victoria Hall. She called the appeals court decision “a fantastic ruling.”

It “shows that open-source groups can protect their code under copyright laws, and this is a ruling that other open-source groups can use,” she said Thursday.

An attorney representing defendants Matthew Katzer and Katzer's company was not available to comment.

Open-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.

Jacobsen had accused Katzer of copying materials from Jacobsen's website and incorporating them into a software package without following the terms of an open-source agreement called the Artistic License.

Artistic License is used for certain free software packages, like Internet encyclopedia Wikipedia.

The lower court, the U.S. District Court for the Northern District of California, had interpreted the Artistic License to permit a user to “modify the material in any way.” But the appeals court said conditions in the Artistic License were vital to enable the copyright holder to retain the ability to benefit from the work of subsequent users.

The appeals court sent the case back to the district court for further proceedings to review Jacobsen's request for a preliminary injunction again.

(Reporting by Martha Graybow)