On June 16, 2015, the Federal Circuit revisited its prior precedent regarding when a claim limitation is subject to 35 U.S.C. § 112, paragraph 6. In Williamson v. Citrix Online, LLC, No. 13-1130 (“Citrix”), the en banc court held that the absence of the word “means” gives rise only to a rebuttable presumption—not a “strong” presumption—that Section 112, paragraph 6 does not apply to the limitation.

BACKGROUND OF SECTION 112, PARAGRAPH 6 -

Section 112, paragraph 6 allows a patentee to recite a claim limitation as a “means or step for performing a specified function,” but “without the recital of structure, material, or acts in support thereof.” Claim limitations drafted in this format, known as “means-plus-function” limitations, are “construed to cover the corresponding structure, materials, or acts described in the specification and equivalents thereof.” If the specification fails to disclose sufficient structure for performing the corresponding function of a means-plus-function limitation, the claim is invalid as indefinite under 35 U.S.C. § 112, paragraph 2.