The Federal Circuit panel deciding Williamson v. Citrix Online, LLC, 770 F.3d 1371 (Fed. Cir. 2014), in November 2014 overturned a district court claim construction that treated the term "distributed learning control module" as a means-plus-function expression under (pre-AIA) 35 U.S.C. § 112, ¶ 6. The patent-in-suit, U.S. Patent No. 6,155,840 ("the '840 patent"), describes methods and systems for distributed or distance learning, enabling presenters to connect to audiences via virtual classrooms. The patent owner conceded that the district court's construction rendered the relevant claims invalid as indefinite, and stipulated to final judgment, followed by an appeal.

On appeal, the Federal Circuit panel held, in line with precedent existing since 2004, that because "distributed learning control module" did not use the word "means," there exists a strong rebuttable presumption that 35 U.S.C. § 112, ¶ 6 does not apply. To rebut the presumption, "it must be demonstrated that 'skilled artisans, after reading the patent, would conclude that [the] claim limitation is so devoid of structure that the drafter constructively engaged in means-plus-function claiming.'" Id. at 1378 (alteration in original) (quoting Inventio AG v. ThyssenKrupp Elevator Ams. Corp., 649 F.3d 1350, 1357 (Fed. Cir. 2011)). In this case, the court found that the word "module" is not the equivalent of "means," because "module" is a structural term, and that the district court did not consider and give weight to the language of the entire claim.

Accordingly, the Federal Circuit vacated the district court's entry of final judgment against Williamson and remanded the case to the district court. On June 16, 2015, the Federal Circuit withdrew its opinion and substituted a new one, including an en banc section (Part II.C.1) addressing the means-plus-function issue. The en banc court reversed the precedent creating a "strong" presumption based on the presence or absence of the word "means." Instead, the court held that 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." Williamson v. Citrix Online, LLC, No. 2013-1130, slip op. at 14 (Fed. Cir. June 16, 2015).

As before, if the claim language does not meet the standard, § 112, ¶ 6 (now § 112(f)) applies. Whereas previously, the analysis appeared almost strictly literal, precedent nevertheless included the notion that the claims were to be analyzed by how they were understood by one of skill in the art. Greenberg v. Ethicon Endo-Surgery, Inc., 91 F.3d 1580, 1583 (Fed. Cir. 1996). The new standard removes the "strong" presumption and loosens the tethers of the means- and step-plus-function analysis from the absence of the word "means," relying only on the person of skill in the art's understanding by a preponderance of the evidence.

The Federal Circuit's decision, authored by Judge Linn, is not coy about the court's motivation for its reversal of precedent.

Our consideration of this case has led us to conclude that such a heightened burden is unjustified and that we should abandon characterizing as "strong" the presumption that a limitation lacking the word "means" is not subject to § 112, para. 6. That characterization is 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. It has shifted the balance struck by Congress in passing § 112, para. 6 and has resulted in a proliferation of functional claiming untethered to § 112, para. 6 and free of the strictures set forth in the statute. Henceforth, we will apply the presumption . . . 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."

Williamson, No. 2013-1130, slip op. at 15-16. The implications of this decision will be felt for many years to come in patent litigation if Judge Linn is correct that there has been a "proliferation of functional claiming untethered to § 112, para. 6 and free of the strictures set forth in the statute." Id. The question to be answered is at what point in the intersection of functional and structural language the scale tips toward language invoking § 112's means- or step-plus-function. Pre-AIA § 112, ¶ 6 and post-AIA § 112(f) are identical and read as follows, with the strictures referred to by Judge Linn in italics:

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.

Squarely in the cross-hairs of the new paradigm1 are recitations that do not use the word "means" but instead use "nonce" words, such as "module," in the case at hand. It is difficult to ignore the fact that the technology in the Williamson case is software, and the court's objection to "black box" claim elements will likely hit hardest in the software and electronics classes. Modern electronics structures are oftentimes quite secondary to their software coding for functionality, and even exact disclosure of the structure of an electronic component performing a function, such as a "processsor," may not satisfy a court or a patent examiner that adequate structure has been disclosed. The term "processor" could indeed be a "nonce" word just as "module" was found to be.

Once § 112 is invoked, the Federal Circuit restated the governing case law that 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, citing Noah Systems, Inc. v. Intuit Inc., 675 F.3d 1302, 1311 (Fed. Cir. 2012) (citing B. Braun Med., Inc. v. Abbott Labs., 124 F.3d 1419, 1424 (Fed. Cir. 1997)). The court further restated that even if the specification discloses corresponding structure, the disclosure must be of "adequate" corresponding structure to achieve the claimed function. Id. at 1311-12 (citing In re Donaldson Co., 16 F.3d 1189, 1195 (Fed. Cir. 1994) (en banc)).

With this decision, the en banc court increases the burden on patent prosecutors. As Judge Newman noted in her dissent, invoking means-plus-function treatment of a claim limitation used to be under the control of the patent draftsperson, resident in the choice to use the term "means for" (or "step for"), or not. Moving forward, under 35 U.S.C. § 112, ¶¶ 2 and 6, 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. Id. at 1312 (citing AllVoice Computing PLC v. Nuance Commc'ns, Inc., 504 F.3d 1236, 1241 (Fed. Cir. 2007)).

If means-plus-function treatment is not desired, then specific structural claiming is required to support a functional recitation in the body of the claim. Further, to safeguard against invalidity due to indefiniteness in the event means-plus-function is invoked by a court, the specification should also contain detailed structural disclosure, clearly linked to the functions recited in the claims. For patents granted with claims using functional language unsupported by detailed specifications, the consequences of falling under § 112, ¶ 6 (now § 112(f)) are charted by the patentee in this case—death by indefiniteness for lack of definite structure.

Footnote

1. The "new" paradigm is essentially the state of the law before 2004, when the Federal Circuit established the "strong presumption" in a line of cases beginning with Lighting World, Inc. v. Birchwood Lighting, Inc., 382 F.3d 1354 (Fed. Cir. 2004).

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.