"The GPL threatens the strategy that Microsoft uses to maintain its monopoly," reads the statement signed by, among others, Linux creator Linus Torvalds, Red Hat co-founder Bob Young, VA Linux Systems CEO Larry Augustin, publisher Tim O'Reilly and Free Software Foundation guru Richard Stallman.
"Microsoft claims that Free Software fosters incompatible 'code forking,' but Microsoft is the real motor of incompatibility: They deliberately make new versions incompatible with old ones to force users to purchase each upgrade," the 10 evangelists said in the statement.
Joining Torvalds in endorsing the statement were free-software evangelist Bruce Perens, open-source advocate Eric Raymond, GNOME desktop founder Miguel de Icaza, Perl programming-language creator Larry Wall and Python language creator Guido van Rossum.
Almost two weeks ago, in a speech to New York University's business school, Microsoft Senior Vice President Craig Mundie took free-software licensing to task for allegedly leeching intellectual property rights away from corporations, opening security holes and just generally being "unhealthy" for the software business.
The speech was the latest attack by the software giant against the open-source community, which has steadily become a threat to Redmond, Wash.-based Microsoft. Three months ago, Jim Allchin, senior vice president for Windows, slammed the movement for allegedly undermining intellectual property law in the United States.
"Open source is an intellectual-property destroyer," Allchin said in February. Microsoft has repeatedly warned U.S. lawmakers that open-source software is undermining property rights. "I can't imagine something that could be worse than this for the software business and the intellectual-property business."
The statement released Tuesday takes aim at such allegations. In particular it defends the GNU General Public License, calling it "the computer equivalent of share and share alike."
The GPL "does not mean, as Microsoft claims, that a company using these programs is legally obliged to make all its software and data free," said the group.
The group instead argues that Microsoft licenses have done more to restrict innovation in software.
"Microsoft license violations have resulted in civil suits and imprisonment," the group said. "Accidental GPL violations are easily remedied, and rarely get to court."
Late Tuesday, Microsoft responded to the open letter. "We appreciate the dialog on this issue--it's exactly the type of discussion Craig was hoping to foster," the company said in a statement.