In WILLIAMSON v. CITRIX ONLINE, LLC, Appeal No. 2013-1130, the en banc Federal Circuit reversed the precedent creating a “strong” presumption that 35 U.S.C. § 112, sixth paragraph, does not apply when a claim does not use the term “means for.” The standard is now “whether the words of the claim are understood by person of ordinary skill in the art to have a sufficiently definite meaning as the name for structure.”  If the words of the claim do not meet that standard, the statute applies.

In an earlier panel opinion, 770 F.3d 1371 (Fed. Cir. 2014), the majority held use of the word “module” does not invoke the means-plus-function language of § 112, sixth paragraph, and the claim was not indefinite.  In reaching that conclusion, the majority held that, because the claim did not use the word “means,” there was a “strong presumption” the statute does not apply.  Citrix sought en banc review.

The en banc Federal Circuit considered the strong presumption and eliminated it.  “The standard is whether the words of the claim are understood by persons of ordinary skill in the art to have a sufficiently definite meaning as the name for structure.  When a claim term lacks the word ‘means,’ the presumption can be overcome and [the statute] will apply if the challenger demonstrates that the claim term fails to ‘recite sufficiently definite structure’ or else recites ‘function without reciting sufficient structure for performing that function.’  The converse presumption remains unaffected: ‘use of the word ‘means’ creates a presumption [the statute] applies.’”

The Federal Circuit concluded the term in question (module) was “a well-known nonce word that can operate as a substitute for ‘means’” in the context of § 112, sixth paragraph, and the claim did not recite sufficiently definite structure.  The Federal Circuit then moved to the second step of means-plus-function construction to determine if the specification disclosed corresponding structure.  Because the specification did not disclose adequate corresponding structure, the claim was indefinite.