UPDATED: Microsoft has renewed its assault on open source software with a claim that open source operating systems violate over 200 of its patents. The claim joins a long list of Microsoft anti-open source patent claims.
Microsoft General Counsel Brad Smith has told Fortune magazine that open source software breaks 235 of its patents. He said that 42 of those were broken by the kernel, or core, of the Linux operating system, while the Linux graphical interface violates 65 of its patents.
Microsoft has in the past sought to undermine the legal basis of open source software. Chief executive Steve Ballmer said in 2004 that a report had claimed that 228 Microsoft patents were violated by open source software.
The author of that report disowned Ballmer's remarks, saying that his report only said that the software potentially violated the patents, and that most software potentially violated the patents.
"Open source faces no more, if not less, legal risk than proprietary software," report author Ravicher told technology news site eWeek in 2004. "The market needs to understand that the study Microsoft is citing actually proves the opposite of what they claim it does."
Microsoft is now making claims based on its own evidence, though it will not specify exactly what patents are infringed. "This is not a case of some accidental, unknowing infringement," Microsoft vice president for intellectual property and licensing Horacio Gutierrez told Fortune. "There is an overwhelming number of patents being infringed."
Ballmer has hit the headlines before for claiming that Microsoft's intellectual property rights are infringed by open source software development. Following a deal with Novell over its version of Linux, Ballmer said that every Linux user owed Microsoft money for using its intellectual property.
Editor's note, 16/05/2007: This story has been amended since it first appeared.