Since at least 1998, the Federal Circuit has held that when a
patent uses the word "means" in a claim element, that
creates a "rebuttable presumption" that the limitation is
a means-plus-function limitation to which Paragraph 6 of 35 U.S.C.
§ 112 applies. The converse also creates a
presumption—if the claim fails to use the word
"means," it is presumed not to be a means-plus-function
element.
Starting with its 2004 decision in Lighting World, Inc. v.
Birchwood Lighting, Inc., 382 F.3d 1354 (Fed. Cir. 2004), the
Federal Circuit's opinions began characterizing the presumption
that flowed from the absence of the word "means" as
"a strong one that is not readily overcome," thereby
making the presumption virtually conclusive in many, if not most,
cases.
However, on June 16, 2015, the Federal Circuit issued a revised
opinion in Williamson v. Citrix Online, LLC, No. 13-1130,
overruling prior decisions characterizing this presumption as
"strong" and holding that the court "will apply the
presumption as we have done prior to" its decision in
Lighting World, "without requiring any heightened
evidentiary showing." The court also "overrule[d] the
strict requirement of 'a showing that the limitation
essentially is devoid of anything that can be construed as
structure.'"
Instead, the standard is now to be "whether the words of a
claim are understood by persons of ordinary skill in the art to
have a sufficiently definite meaning as the name for
structure." The presumption that a claim term lacking the word
"means" does not invoke paragraph 6 of section 112,
therefore, can be overcome "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 rebuttable presumption, that a claim limitation containing
the word "means" is to be construed as a
means-plus-function limitation, remains unaffected.
Because it involved overruling prior precedent, the Federal Circuit
reached this decision by resolving this limited legal issue with
the full en banc court. Judge Newman, alone,
dissented.
This decision will have important consequences not only in
litigation but in claim drafting as well, particularly in areas
like computer software and the electronic arts, where
means-plus-function claiming is prominently used.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
