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Failure to Disclose Corresponding Structure Renders Means-Plus-Function Claims Invalid

July 11, 2002

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Last Month at the Federal Circuit - August 2002

Judges: Gajarsa (author), Newman, and Prost

In Cardiac Pacemakers, Inc. v. St. Jude Medical, Inc., No. 01-1198 (Fed. Cir. July 11, 2002), the Federal Circuit affirmed the district court’s finding that the asserted claims of U.S. Patent No. 4,572,191 (“the ‘191 patent”) are invalid under 35 U.S.C. § 112, ¶ 2, for failing to disclose structure corresponding to a means element of a means-plus-function claim.

Cardiac Pacemakers, Inc. (“CPI”) brought suit against St. Jude Medical, Inc. (“St. Jude”), claiming that St. Jude infringed the ‘191 patent, which relates to implantable cardiac defibrillators. The only independent claim of the ‘191 patent recites, in part, a “cardioverting device comprising… third monitoring means for monitoring the ECG signal produced by said detecting means for activating said charging means in the presence of abnormal cardiac rhythm in need of correction.” The district court concluded that the “third monitoring means” could not be construed because the ‘191 patent specification discloses no corresponding structure. The parties then stipulated that under the district court’s claim construction, the ‘191 patent was invalid.

On appeal, the Federal Circuit concluded that the “third monitoring means” performs the dual functions of monitoring the ECG and activating the charging means. To arrive at this conclusion, the Court noted that the prosecution history includes a version of the claim reciting only the “for activating” phrase, indicating that CPI regarded it as a function rather than a purpose for monitoring the ECG. The prosecution history also includes a version of the claim in which the “for monitoring” and “for activating” phrases are connected by the conjunction “and”—implying that the claimed means performed two functions.
The Federal Circuit also concluded that although, generally, the functions performed by a generic means may be performed by more than one structure, here the claim language requires that both functions be performed by a single structure. The Court reasoned that the claim does not simply recite a generic means for performing two functions, but instead specifically recites a “third monitoring means” for performing the two functions. According to the Federal Circuit, the recitation of a specific means, rather than generic means, mandates that the claimed function be performed by a single means and hence a single structure. As a result, the Federal Circuit concluded that the specification must disclose a single structure that both monitors the ECG signal and activates the charging device.

The Federal Circuit then found that the only entity referenced by the ‘191 patent specification capable of both monitoring and activating is a physician. CPI had conceded, however, that the disclosed physician was not corresponding structure. The Federal Circuit rejected CPI’s arguments that the console used by the physician to monitor the ECG and the button used by the physician to activate the charging means were the corresponding structure. The Court held that it is not sufficient to disclose structure that enables the physician to perform the claimed function. Furthermore, the Court held that even if the console and button did perform the claimed functions, the claim requires a single structure to perform both functions. The Federal Circuit therefore concluded that the claims of the ‘191 patent are invalid because the specification fails to disclose structure corresponding to the claimed “third monitoring means.”