In Microsoft Corp. v. i4i Limited Partnership, a unanimous Supreme Court held last week that an accused infringer must prove the facts underlying any challenge to the validity of a United States patent by clear and convincing evidence.
Under 35 U.S.C. § 282, “[a] patent shall be presumed valid” and “[t]he burden of establishing invalidity . . . rest[s] upon the party asserting” such invalidity. Writing for the Court, Justice Sotomayor interpreted this language as codifying not only the burden of proof to establish invalidity, but also a heightened standard of proof rooted in the common law and recognized in Supreme Court jurisprudence dating back to the 19th century.
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