The Supreme Court of the United States (SCOTUS) ruled today against Microsoft in its appeal of a $290 million jury verdict for infringing Canadian software company i4i’s patent. It wasn’t close. SCOTUS unanimously upheld a U.S. appeals court’s ruling against Microsoft.

Microsoft had argued that the courts should adopt a lower burden-of-proof bar for patent violations. Previously, if you’ve been accused of violating a patent you must show “clear and convincing evidence” that the patent is invalid. Microsoft wants the burden of proof to be lowered to “a preponderance of the evidence.” The SCOTUS didn’t buy this argument for one minute.

In the Court’s unanimous decision, Justice Sonia Sotomayor wrote (PDF Link), “We consider whether [a section of the Patent Act of 1952] requires an invalidity defense to be proved by clear and convincing evidence. We hold that it does.”

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