It has been an eventful two weeks for Supreme Court watchers interested in patent law. In the second of two anticipated patent decisions, the Court handed down an 8–0 defeat to Microsoft on its request that a patent invalidity defense be proven by the “preponderance of the evidence” standard used to measure infringement theories, rather than by the more onerous “clear and convincing” standard (at least in circumstances where the evidence in question was not before the U.S. Patent & Trademark Office during the reexamination process).

In rejecting the position advocated by Microsoft and its many amici (a category in which several of our clients count themselves), the Court avoided consideration of the many policy arguments advanced by the parties. Instead, the Court examined a lengthy trail of historical case law from the early 20th century to the present, leading to the conclusion that Congress codified the common–law presumption of patent validity…and by doing so, implicitly adopted a heightened standard of proof that went hand–in–hand with such presumption. Moreover, the Court relied on continued Congressional silence as to the Federal Circuit’s longstanding interpretation of the relevant statutory provision, 35 U.S.C. § 282. While Section 282 and other patent provisions have been amended numerous times over the years, Congress has not acted to recalibrate the standard.

A difficult decision for the patent defense side of the equation, as retention of the “clear and convincing” standard will keep the bar of proof needed to invalidate weak patents high, and higher than the burden on the patent–owner to prove infringement.