On June 16, 2015, the U.S. Court of Appeals for the Federal Circuit, sitting en banc, lowered the hurdle for construing a patent claim in accordance with the sixth paragraph of 35 USC § 112. Williamson v. Citrix Online, LLC, Docket No. 2013-1130 (June 16, 2015). Under the sixth paragraph of 35 USC § 112, patent applicants may use "means for" terminology to define an invention in terms of its function, without claiming the structure necessary to perform that function. However, a claim that invokes the sixth paragraph of 35 USC § 112 is construed to cover only "corresponding structure, material, or acts described in the specification and equivalents thereof" for performing the claimed function. Depending on the level of detail provided by the specification, this type of claim construction can result in a narrowly interpreted claim. Therefore, many patent applicants seek to avoid claim language that has the potential to invoke the sixth paragraph of 35 USC § 112.
In the past, a "strong" presumption against the application of § 112, paragraph 6 existed in the absence of express "means for" terminology in the claim. In Williamson, the Federal Circuit confirmed that the presumption is appropriate, but clarified that it is not a "strong" one. Rather, 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, slip op. at 16 (citing Greenberg v. Ethicon Endo-Surgery, Inc., 91 F.3d 1580, 1583 (Fed. Cir. 1996)). The court went on to explain that "[w]hen a claim term lacks the word ‘means,’ the presumption can be overcome and § 112, paragraph 6 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.’" Williamson, slip op. at 16 (quoting Watts v. XL Sys., Inc., 232 F.3d 877, 880 (Fed. Cir. 2000)).
The patent at issue in Williamson was filed before the effective date of the America Invents Act (AIA) and therefore subject to the pre-AIA version of 35 USC § 112. While the court did not indicate that its holding applies to patent applications filed after the effective date of the AIA, it seems likely that the holding will be relevant to these applications, because the AIA version of the sixth paragraph of 35 USC § 112 (i.e., 35 USC § 112(f)) is substantially the same as the pre-AIA version of the sixth paragraph of 35 USC § 112.
In dissent, Judge Newman contended that the statutory language of the sixth paragraph of 35 USC § 112 is clear that its provisions are not invoked unless a claim element is "expressed as" a "means for." Judge Newman also observed that in the eight years of congressional study to improve the patent system culminating in the AIA, the legislative record is devoid of any proposal to depart from the "strong" presumption embodied in the language of the sixth paragraph of 35 USC 112. In rather blunt terms, Judge Newman predicts that the decision will cause: "additional uncertainty of the patent grant, confusion in its interpretation, invitation to litigation, and disincentive to patent-based innovation."
In light of the Williamson decision, patent applicants should tread carefully when preparing claims with functional limitations, particularly if they do not wish to invoke 35 USC § 112, paragraph 6. Even if express "means for" terminology is avoided, patent applicants will not be afforded a "strong" presumption against the application of 35 USC § 112, paragraph 6.