Arguing Application Of The Means-Plus-Function Limitation To Claim Elements Without Traditional “Means” Language
Arguing Application of the Means-Plus-Function Limitation To Claim Elements Without Traditional “Means” Language
D. Joshua Smith
(January 2004)
The means-plus-function clause, 35 U.S.C. §112, ¶6, has been one of the most litigated sections of the Patent Act. The means-plus-function clause applies to both patentability determination in the United States Patent and Trademark Office and infringement proceedings. In re Donaldson, 16 F.3d 1189, 1193, 29 U.S.PQ. 1845 (Fed.Cir.1994). Therefore, knowledge of when and how the means-plus-function limitation applies is essential whether working as a litigator or a patent prosecutor.
Title 35 of the United States Code, Section 112, paragraph 6, provides: “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 supports thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” Accordingly, a patentee may generically define a structure for performing a particular function through the use of a means expression, provided that the specified structures corresponding to the means are disclosed in the patent specification. Warner-Jenkinson Co., Inc. v. Hilton Davis Chemical Co., 520 U.S. 17, 28 (1997). In other words, although an applicant may choose “means-plus-function” claim language rather than specifically describing the structures of his invention, the scope of the “means” for performing the stated function must be limited to the structure he specifically disclosed in the specification, and equivalents thereof. The limitation is generally known as the “means-plus-function” or “step-plus-function” limitation.
A claim that uses the word “means” or “step for” invokes a rebuttable presumption that §112, ¶6 applies. On the other hand, a claim that does not use such language,...
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