The German Bundespatentgericht (Federal Patent Court of Germany, BPatG) held the Microsoft patent on FAT to be void and of no force.

The court held that “common name space for long and short filenames” is invalid in its entirety (including Microsoft’s proposed amendments) because the court found that all of the elements distinguishing the patented invention from the prior art (which includes a Linus Torvalds post to a mailing list) did not satisfy the technicity requirement under European patent law. 

The court reversed a prior decision and it expected further appellate action that potentially could reversed its decision.

Article 52 of the European Patent Convention, the article in European patent law that prohibits patents on computer programs “as such”.

Microsoft has the option for further appeal. However in light of the prior art in the court’s ruling it’s unlikely to be viable.


FAT existed with CP/M computers in 1977. Microsoft copied this with PC-DOS including the file control blocks (FCB). Even the 8.3 file naming was copied. The US Patent Office is often remiss to assign patents when something is an obvious copy.