US government officials have supported Microsoft’s attempts to keep hold of two vital file system patents.
The patents are used to support Microsoft’s main Windows file-storage system, and the decision comes after the US patent office initially rejected the patents last autumn.
The Public Patent Foundation, which campaigns for fair patenting, originally asked the US patent office to re-examine the patents almost two years ago.
The foundation claimed there was “prior art” to Microsoft’s patents which were accordingly invalid. The organisation also feared that Microsoft would demand royalties from Linux developers using the technology.
But patent investigators have now ruled that Microsoft’s File Allocation Table file system was "novel and non-obvious", so the company is entitled to the patents.
The FAT file storage system was originally developed for Windows, but is also used on removable flash memory cards, and in some Linux- and Unix-based solutions to enable the exchange of data with Windows system.
Microsoft has already demonstrated its intention to license the patents, having struck a deal with flash memory company Lexar Media in 2003.
Under the general public licence used for many Linux distributions, an open-source developer cannot issue software if it is subject to royalty payments.
Microsoft has not said whether it intends pursue Linux developers using technology covered by the patents.