The open-source community was celebrating this week after a US Court of Appeals decision found that users failing to abide by the terms of open-source licences could be found guilty of copyright infringement.

The ruling was hailed as "huge" by Stanford Law School professor Lawrence Lessig.

"In non-technical terms, the Court has held that free licences such as the Creative Commons licences set conditions on the use of copyrighted work," he wrote in a blog posting. "When you violate the condition, the licence disappears, meaning you're simply a copyright infringer."

The dispute revolved around whether commercial software developer Matthew Katzer had ignored the terms of the open-source Artistic Licence when he took the code of Robert Jacobsen and used it to develop his own commercial software.

The rules of an Artistic Licence state that anyone using free open-source code must attribute the author, highlight the original source of the files and explain how the code has been changed.

Laurent Lachal, head of open source at analyst firm Ovum, said the ruling is unlikely to change firms' perception of open source software or the likelihood of them investing in it.

"Open source is a large movement and this is one relatively minor license among many different open source licenses, so even if the ruling had not come it wouldn't have made the open source movement collapse," he added. "But it's a nice step forward saying that actually one of the licenses is enforceable, which is a good thing,"

Matt Asay, vice president of business development at open source ECM company Alfresco said the ruling would send out a strong message to any firm looking to use open source code in its products.

"I know a range of open source projects where companies came along and took their code with impunity on the assumption no-one could do anything," he explained. "So this ruling gives all open source licenses stronger ground to say 'you have to respect our IP'."