A new ruling offes greater protection against copyright infringement on open-source software.

The case concerns a company, Kam Industries, that downloaded open-source code for use in a product that programs the chips that control model trains.

The code used was written by Robert Jacobsen, who released it under an Artistic License, which requires other people who use it to give credit to the author, identify the original source of the files and describe how the new code has been changed, among other conditions.

Jacobsen alleged Kam Industries violated those terms and in turn violated the software's copyright. He sought an injunction to prevent Kam from using the software, which was denied by a Californian court. However, the US Court of Appeals overturned the ruling this week.

The key point in the ruling is that it gives those who use the Artistic License the leverage to also argue copyright infringement rather than just breach of contract.

That distinction is important, said Andy Updegrove, an attorney with Gesmer Updegrove LLP. Under contract law, the remedy is monetary damages, which aren't likely to amount to anything involving open-source software that is given away, Updegrove said.

However, statutory damages or money that it awarded for a violation of law, can be awarded for copyright infringement without requiring proof of monetary damages, Updegrove said. Also, people can recover attorney fees for copyright infringement cases, he said.

"And, most importantly for licences such as the GPL, it means that your rights to use the copyrighted work at all disappear," Updegrove said, referring to the General Public License, widely used for open source software.

The right to claim copyright infringement is important for other economic reasons, the appeals court said. Even though open-source software is given away for free, the terms under which that software is distributed can be crucial in fostering other money-making products.

"The lack of money changing hands in open-source licensing should not be presumed to mean that there is no economic consideration," the court ruling said. "For example, program creators may generate market share for their programs by providing certain components free of charge."

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