A New York nonprofit patent group has claimed that a seven-year-old patent Microsoft holds for the FAT file system is invalid.
Daniel Ravicher, executive director of the Public Patent Foundation, has requested the US Patent and Trademark Office in Washington to conduct a review because previous patents had already been issued on the same technology.
Ravicher, a patent and trademark attorney who also specialises in open-source legal issues, said he filed the complaint because Microsoft began a campaign late last year to license some of its patents, including the patent for the company's File Allocation Table (Fat) file system.
He alleged that Microsoft wants to control the licensing of the Fat system so it can discourage open-source and free software by not allowing it to be interchangeable with Microsoft software.
The issue Ravicher presented to the Patent Office, however, argues that the patent should never have been issued to Microsoft in November 1996 because "prior art", or evidence that someone else had previously applied for and received a patent for the idea, exists.
"There's presumed to be harm on everyone if a patent is issued where it shouldn't be issued," Ravicher said. "The patent is causing immeasurable injury to the public by serving as a tool to enlarge Microsoft's monopoly while also preventing competition."
Microsoft applied for the patent in 1993, according to patent records. The Fat system was originally created in the mid-1970s.
Microsoft spokesman Mark Martin said the company had not yet received a copy of the group's letter to the patent office. "We're unfamiliar with this organisation and unclear why they are so interested in this one patent," he added.
"Companies asked Microsoft to license our Fat specification and patents to help improve interoperability, and we have entered into a number of such licences."
Fat is an organisational system used to keep track of where data is stored on a storage disc so the data can be found and used by the machine. It is used in computers and other digital devices, including digital cameras and detachable storage media.
The affected patent will continue to be held by Microsoft until 2013, when it will expire under US patent law.
"We'd like to give Microsoft the benefit of the doubt and believe that they are not adopting a strategy of foreclosing competition through the use of dubious patents," Ravicher said. "Unfortunately, their past anticompetitive behaviour, combined with their recent launch of a comprehensive patent assertion campaign, causes us to have serious concerns about their intentions.
"In the end, our beef is not with Microsoft per se," he added. "It's with our broken patent system that is completely failing to ensure only deserving patents get issued."
A spokesman for the patent office could not be reached for comment.
Todd R Weiss writes for Computerworld