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Ruling In Your Case May Depend On Whether 112(6) Applies

Posted on Dec 5, 2014 in Articles

This article originally appeared in Law360 on December 5, 2014.

Whether prosecuting a U.S. patent application, or litigating a U.S. patent, patent practitioners must consider the implications of 35 U.S.C. §112(6).[1] These implications are significant, because whether or not 112(6) applies to a claim can determine claim construction or can render a claim indefinite and thus invalid.

In 2014, the issue of whether claims invoke 112(6) was considered by the Court of Appeals for the Federal Circuit multiple times. Understanding the court’s opinions is important for drafting enforceable claims, giving those claims their desired breadth, and understanding how claims may be interpreted if asserted.

Four cases that considered 112(6) are noteworthy, and the following chart summarizes the issues discussed in this article:



35 U.S.C. 112(6) states:

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.

In 1952, 35 U.S.C. 112(6) was enacted by Congress to statutorily reverse the U.S. Supreme Court, which had invalidated a claim that included functional claim language (see Halliburton v. Walker, 329 U.S. 1 (1946)). “[It] was Congress’s intent to restore the law regarding broad functional language in combination claims to its state prior to Halliburton.” In re Donaldson, 29 USPQ 2d 1845, 1849 (Fed. Cir. 1994).

Thus by statute, Congress provided that claim language may describe a means for performing a function. In order to use this claim language format, “the patent specification must disclose with sufficient particularity the corresponding structure for performing the claimed function and clearly link that structure to the function.” Ibormeith IP LLC v. Mercedes-Benz USA LLC, 732 F. 3d 1376, 1379 (Fed. Cir. 2013).

Whether 112(6) applies to claim language requires a two-step process:

1. First, a determination must be made whether the claim language is drafted in means-plus-function format:

a. Use of the term “means” in the claims triggers a rebuttable presumption that 112(6) applies.

b. Lack of the term “means” in the claims results in a presumption that 112(6) does not apply, BUT the presumption can be overcome if “the claim term fails to ‘recite sufficiently definite structure’ or else recites ‘function without reciting sufficient structure for performing that function.’” Bosch.

2. If 112(6) applies pursuant to step 1), then the claim language is construed by locating the “corresponding structure, material, or acts described in the specification” to which the claim term will be limited. Bosch (citing Welker Bearing Co. v. PHD, Inc. 550 F.3d 1090 (Fed. Cir. 2008)).

Thus, if the claim’s language is covered by 112(6), the claim’s construction is affected because the claim is limited by structure, material or acts described in the specification; however, if 112(6) applies, and there is no structure in the specification to interpret the claim, the claim language is indefinite.

Apple Inc. v. Motorola Inc.

Apple came to the Federal Circuit after the lower court evaluated a patent that included the claim language “heuristic” and determined that the claim language invoked 112(6), even though the word “means” was not included in the claim. (Other patents were evaluated as well for issues unrelated to 112(6)). Step 1b (above) was applied by the lower court, which made the determination that the claim described functions “without describing the structure necessary to perform the functions.” Having determined that 112(6) applied, the lower court based their claim construction on a disclosed embodiment in the specification. The resulting claim construction led to a decision of non-infringement.

On appeal, the Federal Circuit focused on the lack of the word “means” in the claim. The decision process by the Federal Circuit was as follows:

  • The word “means” was lacking from the claim;
  • A rebuttable presumption was thus in place that 112(6) did not apply;
  • The presumption that 112(6) did not apply was “strong,” “not readily overcome” and the court has “seldom” found claim language to be mean-plus-function without the word “means.”

The Federal Circuit then concluded that 112(6) did not apply to the claims, and explained that the district court made “erroneous findings” that “led it to incorrectly conclude that Motorola had rebutted this strong presumption.” Cases were cited that held that when a patentee invokes computer-implemented means-plus-function claiming, an algorithm must be disclosed in the specification as a corresponding structure unless a general purpose computer is sufficient for performing the function (see for example, Aristrocrat Techs. Austl. Pty Ltd. V. Int’l Game Tech., 521 F.3d 1328 (Fed. Cir. 2008)).

The district court’s conclusion was considered erroneous, however, because Aristrocrat (and the other cited cases) were based on claims that explicitly used the word “means.” If the word “means” is lacking from the claim, then Aristocrat does not automatically apply. The inquiry the district court should have used was “whether the limitation, read in light of the remaining claim language, specification, prosecution history, and relevant extrinsic evidence, has sufficiently definite structure to a person of ordinary skill in the art.” And, furthermore, “A limitation has sufficient structure when it recites a claim term with a structural definition that is either provided in the specification or generally known in the art.”

Apple’s claim language and specification disclosed a heuristics operation. A page and half of the Federal Circuit’s decision included examples of how Apple’s patent explained that operation. Not only did the decision provide details, column numbers, and specific examples from the patent, three figures from the patent were reproduced in the decision in order to explain how Apple described the heuristics operation. The decision added that the other claim language, prosecution history, and relevant extrinsic evidence can demonstrate that claim language avoids invocation of 112(6). Based on the conclusion that (1) the heuristic claim limitations provided “sufficient definite structure” and (2) there was a lack of a rebuttal against the “strong presumption against means-plus-function claiming,” the Federal Circuit reversed the district court’s construction that the claim limitations were drafted in means-plus-function format. Summary judgment of noninfringement for one of the asserted patents was thus vacated.


  • When the word “means” is lacking from a claim, the presumption is strong that 112(6) is not intended to apply.
  • When the word “means” is lacking from a claim, the question of whether 112(6) should apply is answered by evaluating whether a claim limitation, read in light of the other claim language, specification, prosecution history, and relevant extrinsic evidence, has sufficiently definite structure to a person of ordinary skill in the art.
  • Disclosure in the specification of the structural details corresponding to the claim language can be helpful to avoid invocation of 112(6).

Triton Tech of Texas LLC v. Nintendo Of America Inc.

The Triton Tech decision was very different than the Apple decision because the word “means” actually appeared in the claims. The analysis is simpler than in Apple because it was presumed (and that presumption was not rebutted) that use of the word “means” invoked 112(6). The district court held that the asserted claims were indefinite because the claims used the word “means” and no algorithm was disclosed for performing the claimed function.

As summarized in the two-step process (above) the question to be addressed by the Federal Circuit was whether the disclosure included “with sufficient particularity the corresponding structure for performing the claimed function” and whether the patent specification clearly linked “that structure to the function.”

Next citing Aristrocrat, the Federal Circuit noted that if a claim element is expressed as a means for performing a function, and if the function “is performed by a general purpose computer or microprocessor, then the specification must also disclose the algorithm that the computer performs to accomplish that function.”

Lacking disclosure of any algorithm, the Federal Circuit affirmed the lower court’s holding that the asserted claims in the patent-in-suit were indefinite. Without disclosure of an algorithm corresponding to the claim language, the requisite structure for performing the claimed function was lacking. Furthermore, that one of ordinary skill in the art might know an algorithm for performing the claimed function “does not rescue the claims.” The Federal Circuit in Triton Tech noted that “[A] bare statement that known techniques or methods can be used does not disclose structure.” After determining that the patent owner had waived an additional argument regarding disclosure of structure, the Federal Circuit affirmed the district court’s ruling that the asserted claims were indefinite.


  • If claims are asserted for which 112(6) is invoked, and an algorithm is required to perform the desired function, lack of disclosure of any algorithm can be fatal to the validity of the claims.
  • That one of ordinary skill in the art may have known an algorithm corresponding to the claim features does not necessarily satisfy the disclosure requirement of 112(6).
  • If there is doubt, the patent drafter should provide an algorithm that corresponds to computer (or microprocessor) based functions.

Robert Bosch LLC v. Snap-On Incorporated

Bosch and Apple differ because Bosch’s claim did not use the term “means” with regard to the language being considered by the Federal Circuit for application of 112(6). The decision, however, is significant because 112(6) was deemed to apply.

While a claim lacking the word “means” is presumed not to invoke 112(6), and the presumption is strong, the question on appeal was whether the “strong” presumption had been overcome. It had not. Central to this inquiry was “if the claim language, read in light of the specification, recites sufficiently definite structure to avoid §112(6).” In addition, “[The] question is whether the claim language names particular structures or, instead, refers only to a general category of whatever may perform specified functions.”

The Federal Circuit further noted that the patent specification “does not contain a single reference to the structure of the [device] itself.” The portions of the specification relied on by the patent owner “provide no structural guidance” and “one of ordinary skill in the art could not find in the specification a definition of the terms as referring to a particular structure.” Concluding that a) the claims included means-plus-function terms; and b) the specification lacked requisite corresponding structure, the court affirmed the holding that the claims in the asserted patent were invalid as indefinite.


  • Claims can be considered to invoke 112(6) even if the phrase “means” is not used.
  • Claim terms that invoke 112(6) are construed in light of the specification, and need to provide sufficiently definite structure to one of ordinary skill in the art, or they may be found invalid as indefinite.

Richard A. Williamson v. Citrix Online LLC

This case was on appeal after the district court construed claim language lacking the word “means” to invoke 112(6). Again, “failure to use the word ‘means’ in a claim limitation created a rebuttable presumption that 35 U.S.C. §112, para. 6 did not apply” and this presumption is a “strong one that is not readily overcome.” Citing Lighting World Inc. v. Birchwood Lighting Inc. 382 F. 3d 1354, 1358 (Fed. Cir. 2004).

The Federal Circuit’s analysis is important because the court:

  • Acknowledged that the supporting specification described the claimed expression “in a high degree of generality.”
  • Consulted dictionaries (on its own initiative) because “we have frequently looked to the dictionary to determine if a disputed term has achieved recognition as a term denoting structure.”
  • Determined that the lower court had erred “in failing to give proper weight to the surrounding context of the rest of the claim language and the supporting text of the specification.”

On the above bases, the court concluded that 112(6) did not apply to the claims in suit, and the lower court’s holding of noninfringement was thus vacated.

Reconciliation of Williamson with Bosch and Apple may be difficult because the specification of the patent in suit in Williamson lacked disclosure of structure corresponding to the contested claim language. In fact, the case included a strong dissent from Judge Jimmie Reyna in which he:

  • Asserted that “[The] claim language explains what the functions are, but does not disclose how the functions are performed.”
  • Cited Bosch for holding that terms invoke 112(6) when they fail to connote sufficient structure.
  • Cited Aristocrat because the patent in suit did not provide an algorithm for performing the claimed function.

Judge Reyna wrote the Apple opinion. Again, in that opinion, significant structure from the patent in suit was identified to conclude that 112(6) did not apply. Judge Reyna also affirmed the Triton holding wherein the claims were found to be indefinite based on a lack of disclosed structure. Perhaps a different panel in Williamson would have yielded a different result.

Of the four cases discussed herein, Williamson is the most recent. On its face, Williamson’s claim language is very functional, and the corresponding structure disclosed in the specification is limited. Thus, while Williamson is a good case to cite when trying to avoid a 112(6) rejection when prosecuting a patent application, a claim drafter would probably be safer putting more detailed disclosure into the specification or drafting the claim to include more structure (as appropriate) to protect the claimed invention.


  • Application of 112(6) to claim language can possibly be avoided by:
    • Using the specification to understand the claims.
    • Using dictionaries.
    • Looking at the words surrounding the claim language in question.
  • The Federal Circuit might agree that 112(6) should not be applied, even though the structure disclosed in the specification is limited. It is even possible that if the court’s decision had been decided by a different panel, there may have been a different result. Practitioners are still advised to ensure that functional claims are accompanied by structural disclosure.

Patent practitioners can walk a fine line between claiming structure and function. In any event, if 35 U.S.C. §112(6) is deemed to apply to the claims, the specification needs to disclose sufficient structure which corresponds to the claimed function.

[1] 35 U.S.C. §112(6) was replaced with 35 U.S.C. §112(f) when the America Invents Act took effect.

– by Lawrence Ashery




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