Microsoft's claims that open-source software infringes its patents do not apply in the UK, according to a top lawyer.
The software giant has said that free software, including Linux and OpenOffice, violates 235 patents that it holds. It has also said it will not sue businesses which use Linux distributions with which it has partnered, such as Novell.
But a leading lawyer, speaking in London on Wednesday, said that those patents do not cover the UK.
"Microsoft's claims are based on US law, which has no application in the UK," said Andrew Katz, a solicitor at Moorcrofts, a Thames Valley-based firm specialising in technology law.
Katz said that Microsoft only has 51 patent applications in the UK, including several failed and pending applications. By contrast, the company has 7,336 patents, and applications for 10,761 more, in the US.
"The possibility of infringement is vastly smaller in the UK," said Katz.
He added that, even if UK companies expand into the US or other countries with different patent regimes, they are unlikely to face any trouble.
Microsoft has said it will not sue for now over the patents, which it has not revealed by name.
As soon as Microsoft reveals the patents involved, it will lose any power over the open-source movement, said Katz, adding that Microsoft would find it difficult to enforce the patents without naming them. "As soon as they do [reveal the violating code], it will be engineered around," he said.
The situation illustrates Europe's more sensible approach, protecting intellectual property in software by copyright rather than patents, the solicitor said. "No-one has come to me with an even slightly convincing argument that a piece of software has been written that would not have been written without software patents," Katz said.
Despite businesses' fears that open-source code may raise legal issues, very few businesses have so far faced any trouble. Katz said: "There are very few decided cases, because they tend not to arise, or reach court. I'm delighted — there isn't that much work for me out there."
Before becoming a lawyer, Katz worked as a software developer, and has released code under the GPL. He has spoken out against software patents for the last three years.
Microsoft could offer no response at the time of writing.