Microsoft signed a deal with Novell, one of the providers of Linux, in which Novell paid it a lump sum in return for a guarantee that Microsoft would not sue Novell's clients for what it calls a violation of its own patents in the Linux program.
The prospect of a drawn-out legal battle with Microsoft, an experienced litigator, could push users of Linux into the hands of Novell and away from dominant Linux provider Red Hat, which does not have such a deal with Microsoft.
Although Linux is free, providers of the system offer the software with packaging, documentation and--most important--installation and maintenance, so any client shift from Red Hat would cost it money.
"Either customers desert Red Hat to go to Novell, to get safety, or Red Hat will be forced into a similar deal with Microsoft," and founding director of the Software Freedom Law Center in New York.
, said Microsoft's deal skirts the , used by Linux and other free programs, which requires the software to be given away.
He and others have started work on updating the license to close the loophole by saying a promise not to sue, such as the one given by Microsoft, would be automatically applicable to everyone.
That would effectively flip Microsoft's agreement on its head and guarantee that no one would face a suit from Microsoft if anyone were protected.
"A clause like that would not be difficult to get community agreement on these days," Moglen said, adding that a change could be ready in weeks or months.
, in which both companies agreed not sue each other's clients for patent violation, Microsoft agreed to pay Novell $348 million, while Novell pays Microsoft $40 million, on the basis that Novell has fewer customers.
Microsoft says it has patent rights to some of the technology in Linux, although it has never said exactly what those rights might be or what patents are involved.
Microsoft Chief Executive Steve Ballmer said if customers bought Linux from anyone but Novell, they could face trouble.
"If a customer says, 'Look, do we have liability for the use of your patented work?' Essentially, if you're using non-Suse Linux, then I'd say the answer is yes," Ballmer told eWeek.com recently, referring to the Linux system sold by Novell.
"I suspect that (customers) will take that issue up with their distributor," Ballmer said, adding that if customers considered doing a direct download of a non-Suse Linux version, "they'll think twice about that."
Microsoft makes the Windows operating system, for which it charges billions of dollars a year, but Linux has been a thorn in the software giant's side because it is freely available.
Linux was created, maintained and improved by volunteers working under a license requiring that it be freely available for copying, modifying and improving.