Williamson v Citrix: Functional Language Without Structural Meaning in System Patent Claims Trigger MPF Section 112(f)

The Patent Appeals court, in an en banc decision, reversed decades of precedent and held that section 112(f) of the Patent Statute, which concerns “means plus function” MPF language should apply to claim limitations which do not have structural meaning without regard to nonce words which replace “means” such as module, mechanism, element, device “and other nonce words that reflect nothing more than verbal constructs.”  Williamson v. Citrix Online, LLC, Case No. 2013-1130 (June 16, 2015) en banc (Williamson v Citrix). Once a court identifies means plus function or MPF in a patent claim, “such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” 35 U.S.C. Section 112(f) (previously Section 112, para. 6).   Accordingly, the Federal Circuit Court of Appeals, which handles all patent appeals from the trial courts, has narrowed mechanical and system patent claims which use functional language, overruling a considerable line of cases dating back to 1991. Those cases indicated that the use of the word “means” in a claim element created a strong rebuttable presumption that section 112(f) applied to functional language following the word “means.”

Per the Court, “In making the assessment of whether the limitation in question is a means – plus – function term subject to the strictures of section 112, para. 6, our cases have emphasized that the essential inquiry is not merely the presence or absence of the word ‘means’ but 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 section 112, para. 6 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.’”

In the Williamson case, defendant Citrix presented evidence that the subject claim limitation “distributed learning control module” does not have a well understood structural meaning in the computer technology field. Further Citrix pointed out to the district court that the “distributed learning control module” limitation was drafted in the same format as a traditional means – plus – function limitation, and merely replaced the term “means” with another “nonce” word, “module,” thereby connoting a generic “black box” for performing the recited computer – implemented functions.

The Federal Circuit listed several words that act as a substitute for “means” in the context of Section 112, MPF including the words module, mechanism, element, device and “other nonce words that reflect nothing more than verbal constructs [which] may be used in a claim in a manner that is tantamount to using the word ‘means’ because they ‘typically do not connote sufficiently definite structure’ and therefore may invoke section 112 para. 6. The Federal Circuit then turned its attention to the specification and found that while the portions of the claim do describe a certain inputs and outputs at a very high level, for example communications between the presenter member computer and the audience member computer, the claim does not describe how the “distributed learning control module” interacts with other components in the “distributed learning control server” in a way that might inform the structural character of the limitation – in – question or otherwise impart structure to the “distributed learning control module” as recited in the claim. The Federal Circuit remanded the case vacating judgment of non-infringement regarding some claims and affirming the District Court’s construction of the claim limitation “distributed learning control module.”

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