Yesterday, the Federal Circuit issued a decision in Williamson v. Citrix that includes an en banc portion that broadens the circumstances in which claim limitations may be deemed means-plus-function limitations.  This appears to be an effort by the court to address concerns that some patent claims directed to computer-implemented or software inventions may be too vague or over broad based on claim limitations directed to general functionality, rather than specific structure or algorithms.  The challenged patent claims in this instance did not provide algorithms or the such in the specification to perform the functions of the limitation construed to be a means-plus-function claim, so the patent claims were held invalid as being indefinite.

So prepare to submit your supplemental authority to the court and revise your claim construction contentions and briefs, because this is a game-changer.  Some computer-implemented or software patent claims drafted in functional language without any algorithm or other structure disclosed in the specification for performing that function may be invalidated.  On the other hand, some computer-implemented or software patent claims with functional language that have algorithms or other structure disclosed in the specification might be saved from an Alice challenge that the claim is invalid under § 101 for attempting to patent an idea (see our June 19, 2014 post on the Supreme Court’s Alice decision).

Summary.  In sum, the Federal Circuit overruled prior precedent concerning a “strong” presumption that claim limitations that do not use the term “means” are not means-plus-function limitations absent “a showing that the limitation essentially is devoid of anything that can be construed of structure.”  Observing that the court seldom held limitations to be means-plus-function limitations under that heightened burden, the court ruled en banc that the heightened burden was “unjustified”, “unwarranted, is uncertain in meaning and application, and has the inappropriate practical effect of placing a thumb on what should otherwise be a balanced analytical scale.”  The Federal Circuit en banc, thus, stated a new standard that is to be based on means-plus-function law that existed before the “strong” presumption:

Henceforth, we will apply the presumption as we have done prior to Lighting World [v. Birchwood Lighting, 382 F.3d 1354 (Fed. Cir. Sep. 3, 2004)], without requiring any heightened evidentiary showing and expressly overrule the characterization of that presumption as “strong.”  We also overrule the strict requirement of “a showing that the limitation essentially is devoid of anything that can be construed as structure.”

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 the structure. Greenberg, 91 F.3d at 1583.  When a claim lacks the word “means”, the presumption can be overcome and § 112 par. 6 [or § 112(f) for post AIA patents] 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.”  Watts, 232 F.3d at 880.  The converse presumption remains unaffected: “use of the word ‘means’ creates a presumption that § 112, ¶ 6 applies.” Personalized Media, 161 F.3d at 703.

In this case, the court found that the limitation at issue, which did not use the term “means” (but used the generic word “module”), was nonetheless subject to interpretation as a means-plus-function limitation.  Such means-plus-function limitations require disclosure in the patent specification of adequate “corresponding structure” to perform the claimed function.  The court found that no such structure was disclosed, because the structure in this case would be a special purpose computer that requires more than disclosing a “general purpose computer or microprocessor”; rather, the specification must “disclose an algorithm for performing the claimed function.”  The court thus held the patent invalid as being indefinite under § 112, ¶ 2 (what is now § 112(b) for post-AIA patents).

AIA STATUTORY NOTE:  The America Invents Act (AIA) took effect on September 16, 2012.  Prior to the AIA, the patent statute addressed means-plus-function limitations in the sixth-paragraph of unenumerated 35 U.S.C. § 112 — hence, referred to as § 112, ¶ 6 means-plus-function limitations.  The AIA added enumeration to § 112 such that means-plus-function limitations are now addressed in § 112(f) (but otherwise unaltered).  Similarly, the definiteness requirement was in the second paragraph of pre-AIA § 112 — hence, referred to as § 112, ¶ 2 indefiniteness validity challenge.  The definiteness requirement in post-AIA is now found in § 112(b).  Which version of § 112 to use depends on whether the application that resulted in the patent-at-issue was filed before Sep. 16, 2012 (pre-AIA) or on/after that date (post-AIA).

Because the application for the patent at issue was filed before Sep. 16, 2012, the court (and hence this post) refers to § 112, ¶ 6.

EN BANC NOTE:  Almost all of this decision is by only the three-judge panel of Judges Moore, Linn (author) and Reyna (concur/dissent).  The en banc court ruled on just one section of the decision:  Section II.C.1 concerning how to determine whether a limitation is a means-plus-function limitation subject to § 112, ¶ 6.  The en banc court consisted of Chief Judge Prost and Judges Newman (dissent), Lourie, Linn, Dyk, Moore, O’Malley, Reyna, Wallach, Taranto, Chen and Hughes.


The trustee for patent owner At Home Corporation Bondholders’ Liquidating Trust filed suit against Citrix, Microsoft, Adobe, Cisco, IBM and others for infringing U.S. Pat. No. 6,155,840 directed to “distributed learning” that “utilize[s] industry standard computer hardware and software linked by a network” to provide a “virtual classroom.”

The means-plus-function issue concerned the “distributed learning control module” limitation in independent Claim 8:

a distributed learning control module for receiving communications transmitted between the presenter and the audience member computer systems and for relaying the communications to an intended receiving computer system and for coordinating the operation of the streaming data module.

The district court’s claim construction order ruled that this limitation was a means-plus-function limitation under § 112, ¶ 6, the patent specification failed to disclose necessary algorithms for performing all of the three claimed functions and, thus, Claim 8 and its dependent claims were invalid as being indefinite under § 112, ¶ 2.


Standard of Review.  As an initial matter, the Federal Circuit ruled that, “[b]ecause the district court’s claim constructions in this case were based solely on the intrinsic record, the Supreme Court’s recent decision in Teva does not require us to review the district court’s claim construction any differently than under the de novo standard we have long applied.” (see our Jan. 23, 2015 post on the Teva decision).  This means that the Federal Circuit reviewed the issue as a matter of law without being required to defer to the district court’s decision on factual issues that otherwise might have arisen if the claim construction involved evidence beyond the patent specification and file history.  (Note that the patent owner did submit technical expert testimony, but the district court did not comment on that testimony so the Federal Circuit did not have a decision thereon to which it would defer).

Standard To Determine Whether Claim Limitation Is A Means-Plus-Function Limitation.  This is the only portion of the decision considered en banc, which was required on this issue because the panel by itself could not overrule prior precedent on this issue.  The Federal Circuit started, of course, with the statutory language at issue:

An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof. [35 U.S.C. § 112, ¶ 6]

The court’s 1998 Personalized Media decision had created a rebuttable presumption that § 112, ¶ 6 applies to a claim limitation if the  term “means” is used in the limitation, which patent drafters traditionally used to denote means-plus-function limitations.  Absent the term “means”, there is a rebuttable presumption that § 112, ¶ 6 does not apply.  The presumptions are rebuttable and, even without the word “means”, § 112, ¶ 6 applies if “the words of the claim are understood by a persons of ordinary skill in the art to have a sufficiently definite meaning as the name for structure.”  The presumption is 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.'”

But in its 2004 Lighting World decision, the Federal Circuit made it harder to overcome the presumption,  stating that “the presumption flowing from the absence of the word ‘means’ is a strong one that is not readily overcome.” [emphasis in original]  The court’s 2012 Flo Healthcare decision rose the bar even further by requiring “a showing that the limitation essentially is devoid of anything that can be construed as structure” before § 112, ¶ 6 would apply in the absence of the word “means” in the claim limitation.  As a result, the court “seldom held that a limitation without recitation of ‘means’ is a means-plus-function limitation.”  The Federal Circuit en banc, thus, overruled that line of decisions as discussed and quoted in the summary at the beginning of this post.

“Distributing Learning Control Module” Is A Means-Plus-Function Limitation.  The court found that the entirety of the “distributing learning control module” limitation is “in a format consistent with traditional means-plus-function claim limitation,” but “replac[ing] the term ‘means’ with the term ‘module’ and recit[ing] three functions performed by the ‘distributed learning control module.” The panel found that the term “module” is “a well-known nonce word that can operate as a substitute for ‘means’ in the context of § 112, para. 6,” stating:

Generic terms such as “mechanism,” “element,” “device,” and other nonce words that reflect nothing more than verbal constructs 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 § 112, para. 6.

Here, the word “module” does not provide any indication of structure for providing the same specified function as if the term “means” had been used.  Indeed, [the patent-owner] acknowledges that “the term ‘module,’ standing alone is capable of operating as a ‘nonce word’ substitute for ‘means.'”

The court found that the prefix “distributed learning control” modifying the word “module” does not “describe a sufficiently definite structure” and the specification uses that term without providing “any structural significance to the term.”  Further, the claim limitation does not describe how the module “interacts with other components … in a way that might inform the structural character of the limitation-in question or otherwise impart structure to” the limitation.  Further, the patent owner’s expert testimony that, based on the patent specification, a skilled artisan “would know exactly how to program” a computer to perform the function does not “create structure where none otherwise is disclosed.”

The court, therefore, ruled that the “distributed learning control module” claim limitation is a means-plus-function limitation to which § 112, ¶ 6 applies .

No Corresponding Structure Disclosed.  The court ruled that the patent specification did not disclose sufficient structure corresponding to the claimed function of the means-plus-function limitation. In this case, there were three claimed functions — (1) receiving communications, (2) relaying the communications and (3) coordinating the operation — and “the patentee must disclose adequate corresponding structure to perform all of the claimed functions.”  The court focused on the third function of coordinating the operation of the streaming data module.  The court described the inquiry for finding corresponding structure, an invalidity for failing to do so, as follows:

Structure disclosed in the specification qualifies as “corresponding structure” if the intrinsic evidence clearly links or associates that structure to the function recited in the claim.  Even if the specification discloses corresponding structure, the disclosure must be of “adequate” corresponding structure to achieve the claimed function.  Under 35 U.S.C. § 112, paras. 2  [indefiniteness] and 6 [means-plus-function], therefore, if a person of ordinary skill in the art would be unable to recognize the structure in the specification and associate it with the corresponding function in the claim, a means-plus-function clause is indefinite.

In this case, a special purpose computer is needed to implement the claimed functions, and the disclosure should provide an algorithm for the special purpose computer to perform the function:

The written description of the ‘840 patent makes clear that the distributed learning control module cannot be implemented in a general purpose computer, but instead must be implemented in a special purpose computer–a general purpose computer programmed to perform particular functions pursuant to instructions from program software.  A special purpose computer is required because the distributed learning control module has specialized functions as outlined in the written description.  In cases such as this, involving a claim limitation that is subject to § 112, para. 6 that must be implemented in special purpose computer, this court has consistently required that the structure disclosed in the specification be more than simply a general purpose computer or microprocessor.  We require that the specification disclose an algorithm for performing the claimed function. The algorithm may be expressed as a mathematical formula, in prose, or as a flow chart, or in any other manner that provides sufficient structure.

In this case, the specification merely disclosed functions of the “distributed learning control module” without setting forth “an algorithm for performing the claimed functions.”  Further, figures in the patent showing representative displays on a computer did not disclose an algorithm for performing the claimed function.  Further, this failure to disclose structure could not be cured by expert testimony about whether one skilled in the art could create structure to perform the function:

The testimony of one of ordinary skill in the art cannot supplant the total absence of structure from the specification.  The prohibition against using expert testimony to create structure where none otherwise exists is a direct consequence of the requirement that the specification adequately disclose corresponding structure.  Thus, the testimony of [technical expert] Dr. Souri cannot create structure where none otherwise exits.

The patent claims were thus held invalid for being indefinite based on “fail[ing] to disclose any structure corresponding to the ‘coordinating’ function of the ‘distributed learning control module.'”