Today EFF, joined by Public Knowledge, the Computer & Communications Industry Association and the Apache Software Foundation, filed an amicus brief asking the U.S. Supreme Court to hear a case in which Microsoft is trying to make it easier to invalidate an issued U.S. patent. If successful, this challenge should help in the fight against bad patents by lowering the standard required to prove that the patent is invalid to the same one required to prove infringement. It should especially help the free and open source community.

Here’s some background: In court, parties have to prove their case by some “standard of proof.” In almost all civil cases, the standard is “preponderance of the evidence” – meaning it is more likely than not that the facts are true. When the question is invalidating a patent, however, the U.S. Court of Appeals for the Federal Circuit decided that a defendant trying to prove a patent invalid must do so by a higher standard than normal civil cases, that of “clear and convincing” evidence. “Clear and convincing” means that the facts are “highly probable,” which is a much more difficult standard to meet when trying to invalidate a patent than just a preponderance.

Microsoft is asking the Supreme Court to consider the Federal Circuit’s standard of proof rule in a case brought against it by i4i Ltd. for patent infringement. i4i claimed its patent covered editing documents containing markup languages like XML (Microsoft Word had XML editing capabilities).

In a case three years ago, the Supreme Court had suggested that this high standard of proof should not apply where the prior art involved was not considered by the Patent Office before it issued the patent. Even still, the Federal Circuit has left the clear and convincing evidence standard untouched. In this case, Microsoft had indeed argued that i4i’s patent was invalid because the disclosed invention had been embodied in a software product sold in the United States more than a year before the patent application was filed – prior art that the patent examiner did not consider.

EFF argues in its brief that the Federal Circuit’s requirement that an accused infringer prove patent invalidity by “clear and convincing” evidence unfairly burdens patent defendants, especially in the free and open source software context. The standard undermines the traditional patent bargain between private patent owners and the public and threatens to impede innovation and the dissemination of knowledge. EFF is of course concerned with the effect illegitimate patents have on innovation.

While the Supreme Court rarely agrees to hear petitions such as Microsoft’s, we hope it will choose to hear this one. It’s long past time to level the patent playing field.