The Federal Circuit Alters The Means-Plus-Function Analysis

The Federal Circuit's recent en banc opinion in Williamson v. Citrix Online, LLC, 2015 U.S. App. LEXIS 10082, *2 (Fed. Cir. June 16, 2015) (Williamson II) may result in courts finding that more claims include "means-plus-function" claim elements, which could significantly affect the scope and validity of those claims. As a result of Williamson II, the Federal Circuit has weakened the "presumption" that claim elements lacking the term "means" fall outside the means-plus-function analysis.

1. "Means-Plus-Function" Claim Elements

   Means-plus-function claim elements are specifically authorized by the Patent Act, which provides that "[a]n 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." 35 U.S.C. § 112(f) (previously 35 U.S.C. § 112, ¶ 6, prior to the America Invents Act). The Patent Act also provides that a means-plus-function element "shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof."

   For example, rather than claiming a nail or a screw as part of an invention, a patentee could instead simply claim a "means for fastening," which would be limited to the corresponding fasteners disclosed in the specification (perhaps, for example, nails, screws, staples, and glue) and equivalents thereof. But without a corresponding structure, material, or acts for performing the claimed function, the claim will be invalid for indefiniteness under 35 U.S.C. § 112(b).

   Thus, a determination that a claim includes a means-plus-function element may greatly impact both the scope of the claim, and how its validity may be challenged. Importantly, however, this determination is not based solely on the presence or absence of the word "means" in the claim.

2. Prior Legal Standard for Claim Elements Without the Term "Means": The "Strong Presumption"

   Before the Federal Circuit's decision in Williamson II, a claim element that actually used the term "means" created a rebuttable presumption that § 112, ¶ 6 applied, and a claim element that did not use the term "means" created a strong rebuttable presumption ("not readily overcome") that § 112, ¶ 6 did not apply. Lighting World, Inc. v. Birchwood Lighting, Inc., 382 F.3d 1354, 1358 (Fed. Cir. 2004). In the absence of the word "means," this strong presumption that § 112, ¶ 6 did not apply could be overcome by proving that...