Supreme Court Rules on Presumption of Patent Validity

June 9, 2011

The U.S. Supreme Court rendered its opinion this morning in Microsoft Corp. v. i4i Limited Partnership.  In short, the question presented by this case is: how strong is the presumption of validity afforded to patents issued by the U.S. Patent and Trademark Office.  The Court today unanimously upheld the strong presumption of patent validity that has been in use since before 1952.

An entity sued for patent infringement may assert a defense of invalidity, showing that the invention at issue does not meet the statutory requirements for receiving patent protection.  The Patent Act of 1952 states that issued patents are “presumed valid.” 35 U.S.C. § 282.  In the i4i case, Microsoft challenged this presumption, arguing that the standard for overcoming the presumption of validity should be a low “preponderance of the evidence” standard, rather than the higher “clear and convincing” standard used by the Court of Appeals for the Federal Circuit.  Microsoft further argued that even if the higher clear and convincing standard is to used for prior art references and other evidence that was considered by the Patent Office during examination of the patent, the lower preponderance standard should be used for evidence that had not been previously considered.  The Supreme Court was not persuaded by either line of argument.  However, the Court did indicate that new evidence of invalidity would likely carry more weight than evidence that was considered and rejected by the Patent Office, and therefore would be more likely to satisfy the higher evidentiary standard.

In its opinion, the Court acknowledged policy arguments both for and against a strong presumption of patent validity, citing law professors Mark Lemley of Stanford and Douglas Lichtman of UCLA.  However, the Court determined that it was bound to follow congressional intent as codified in the 1952 Patent Act, and prior common law precedent.

The Court’s opinion may be downloaded from

If you have any questions regarding this case or other intellectual property law matters, please contact me at 650-287-2163.

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