Four years ago in the landmark decision of KSR International Co. v. Teleflex, Inc., on obviousness, the U.S. Supreme Court declined to reach the intriguing question of whether the presumption of patent validity is weakened due to an invalidity challenge based on prior art that was not presented to the U.S. Patent and Trademark Office (USPTO). The court, however, noted in dicta that the rationale underlying the presumption that the USPTO in its expertise has "approved" the patent claim "seems much diminished here." Since then, there has been a lingering question about the strength of the presumption especially where an invalidity challenge is based on art that was not before the USPTO. On June 9, 2011, the Supreme Court's eagerly-awaited opinion in Microsoft Corp. v. i4i Ltd. Partnership considered Microsoft's challenge to the clear and convincing evidence standard. This comes at a time when criticism of the presumption of validity and the clear and convincing standard has grown significantly. This article discusses i4i, including some interesting considerations the decision raises for the future of patent litigation.

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