On August 12, 2019, the Court of Appeals for the Federal Circuit (“CAFC”) issued an opinion vacating and remanding the obviousness finding of the U.S. Patent and Trademark Office’s Patent Trial and Appeal Board (“PTAB”). MTD Products Inc. v. Iancu
, __ F.3d __ (Fed. Cir. Aug. 12, 2019). The CAFC ruled that the PTAB’s claim construction on which its obviousness finding was premised was incorrect because the construction conflated corresponding structure in the patent’s specification with a structural definition for the term, instead of construing the term as a means-plus-function term under 35 U.S.C. § 112, ¶ 6.
Means-plus-function claiming occurs when a claim term in a patent is drafted in a manner that invokes 35 U.S.C. § 112, ¶ 6:
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.
The first step in determining whether a claim element invokes this provision is by asking whether the claim limitation employs the word “means.” Williamson v. Citrix Online, LLC
, 792 F.3d 1339, 1348 (Fed. Cir. 2015) (en banc). If it does not, there is a rebuttable presumption that the term conveys sufficiently definite structure and is not subject to strictures of § 112, ¶ 6. Id.
However, a challenger can rebut this presumption by demonstrating “that the claim term fails to recite sufficiently definite structure or else recites function without reciting sufficient structure for performing that function.” Id.
(internal quotations omitted). The essential inquiry 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. Id.
If a claim element is found to invoke § 112, ¶ 6, the claim is restricted in its scope of coverage to only the structure, material, or acts described in the specification as corresponding to the claimed function and equivalents thereof. Id.
In November 2015, the Toro Company petitioned for inter partes
review of a patent that MTD Products Inc. asserted against it in the U.S. District Court for the Northern District of Ohio. Toro argued in its petition that the patent, which is directed toward a steering and driving system for zero turn radius (“ZTR”) vehicles, was invalid over certain prior art. MTD responded that the particular claim term in question—a “mechanical control assembly”—is a means-plus-function term, that the corresponding structure for the term is a “ZTR control assembly,” and that the asserted prior art does not disclose a “ZTR control assembly.” In support of this argument, MTD introduced expert testimony that “mechanical control assembly” would not bring to mind any specific structure to a person of ordinary skill in the art. In response, Toro argued that the patent’s specification denoted structure and that during prosecution MTD admitted that “mechanical control assembly” was structural.
The PTAB agreed with MTD that when read in isolation
“mechanical control assembly” would appear to be subject to § 112, ¶ 6, but that when read in the context of the specification and, most persuasively to the PTAB, the prosecution history—during which MTD stated that the claims recite “a mechanical control assembly that is structurally different
from what the [asserted prior art] discloses”; that “the claim language at issue concerns the configuration
of the claimed mechanical control assembly”; and that “the claimed configuration is indeed structural
”—it was clear that “mechanical control assembly” was not governed by § 112, ¶ 6.
The CAFC vacated the PTAB’s decision and remanded the proceedings with instructions for the PTAB to construe “mechanical control assembly” as means-plus-function under § 112, ¶ 6 in its obviousness analysis. The CAFC agreed with the PTAB that “mechanical control assembly” is similar to other generic, black-box words that are generally subject to § 112, ¶ 6, because the term does not connote sufficiently definite structure to one of ordinary skill in the art and because what the “mechanical control structure” is configured to do is functional. However, the CAFC found that the PTAB erred when it relied on the specification’s description of a “ZTR control assembly” to conclude that “mechanical control assembly” has an established structural meaning. The CAFC explained that just because “the specification discloses a structure
corresponding to an asserted means-plus-function claim term does not necessarily mean that the claim term is understood by persons of ordinary skill in the art to connote a specific structure or a class of structures
.” (emphasis added). Thus, the PTAB erred in this regard in conflating the two distinct inquiries of the means-plus-function test. With respect to MTD’s statements during prosecution, the CAFC explained that the statements were not made within the context of § 112, ¶ 6, and were therefore not persuasive because they were taken out of context.