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ARTICLE · 01 JULY 2005

Expert Testimony is no Substitute for Disclosure of Structure Supporting a Means-Plus-Function Claim Element

McDermott Will & Emery
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In affirming the district court’s summary judgment of invalidity for indefiniteness, the U.S. Court of Appeals for the Federal Circuit held that structures corresponding to a means-plus-function element must be disclosed in the specification; an expert’s testimony concerning what unlisted structures one of ordinary skill would understand are present cannot substitute for this requirement.

United StatesIntellectual Property
Michael Wilcox
Michael Wilcox
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In affirming the district court’s summary judgment of invalidity for indefiniteness, the U.S. Court of Appeals for the Federal Circuit held that structures corresponding to a means-plus-function element must be disclosed in the specification; an expert’s testimony concerning what unlisted structures one of ordinary skill would understand are present cannot substitute for this requirement. Default Proof Credit Card System, Inc. v. Home Depot, U.S.A., Inc., Case No. 05-1069 (Fed. Cir. Jun. 16, 2005) (Michel, C.J.).

Default’s patent-in-suit claims a machine allowing customers to purchase prepaid debit cards for use with participating merchants. The system consists of a "point-of-sale assembly" allowing the user to pay for the card, a "means for dispensing" a debit card having a unique identification number and a remote "clearing house assembly" that stores, processes and communicates the card information to the merchant. The claims contain multiple means-plus-function elements. The

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