The OIN had already supported navigation software maker TomTom in their court case against Microsoft. As the case unfolded, TomTom consented to pay Microsoft and remove from its software two functions related to three FAT-LFN patents (5579517, 5758352 and 6256642).

To spare further companies from problems with the questionable three patents, the OIN together with Linux Defenders have now posted the patents on http://www.post-issue.org for general review by the community. The issue is prior art, a legal term referring to proof that techniques used in a patent existed prior to its application. In the case of FAT files, this was creation and intelligent handling of long and short filenames. The OIN hopes that through public examination of prior art, the United States Patent and Trademark Office (USPTO) might invalidate the FAT patents, thereby exonerating TomTom.

According to a report by Linux-Watch.com, the chances of finding software to support the prior art claim are pretty good. The technical lead at OIN, Keith Bergelt, is confident that help from the community can contribute to invalidating the patents by year's end: "Significant prior art has already been identified concerning these patents, and this will enhance and expand upon that evidence." To speed up the process, many more prior art examples need to be brought to the fore.

An intermediate solution is "no FAT, not patents." Recognizing that the USPTO is currently overburdened, the OIN is advising hardware providers to excise the Microsoft FAT filesystem from their systems, and the Linux Foundation is helping in this endeavor to find appropriate alternatives. OIN's Bergelt doesn't think that Microsoft will go after any further companies based on their FAT patents, but invalidation should help in support against any future claims.