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Accused Satellite Is “Outside the Orbit” of the Doctrine of Equivalents

April 30, 2001

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Last Month at the Federal Circuit - May 2001

Judges: Gajarsa (author), Schall, and Friedman

In Lockheed Martin Corp. v. Space Systems/Loral, Inc., No. 00-1310 (Fed. Cir. Apr. 30, 2001), the Federal Circuit affirmed a grant of SJ of noninfringement to Space Systems/Loral, Inc. (“SSL”) after finding that prosecution history estoppel prevented the application of the DOE.

In 1995, a predecessor of Lockheed Martin Corporation (“Lockheed”), assignee of U.S. Patent No. 4,084,772 (“the ‘772 patent”), filed suit accusing SSL of building satellites that infringe the ‘772 patent. The ‘772 patent relates to a control system for pointing the antennae of a geosynchronous orbiting satellite at a desired target on earth. To point its antennae, a satellite uses the angular momentum created by a spinning reaction wheel to roll about a particular axis. Rolling aims the satellite’s antennae in a desired direction.

The primary disputed limitation of the ‘772 patent recites “means for rotating said wheel in accordance with a predetermined rate schedule which varies sinusoidally over the orbit at the orbital frequency of the satellite.” After a Markman hearing, the district court had found that “varies sinusoidally” means “a sine-shaped variation that passes through zero.” In terms of the motion of a reaction wheel, the wheel would have to slow, stop, and reverse direction to literally meet this limitation. Because the parties agreed that the accused SSL satellite’s wheel did not stop and reverse direction, the district court had granted SJ of no literal infringement.

The district court also held that the SSL satellite did not infringe under the DOE. The district court determined that the function of the limitation was rotating the wheel by way of using a predetermined rate schedule that varies sinusoidally, with the result being that the satellite is rolled to point at a desired target. Because it was undisputed that the wheel of the accused SSL satellite did not pass through zero, the district court had ruled that the “way” the SSL wheel operated was not substantially similar to that claimed in the ‘772 patent.

On appeal, Lockheed conceded that the SSL satellite did not literally infringe the ‘772 patent claims. Lockheed argued, however, that based on the testimony of its expert, a factual dispute existed as to whether the accused satellite contains an equivalent to the disputed limitation, thus making the grant of SJ of noninfringement under the DOE improper.

The Federal Circuit found no fault with the district court’s construction of the limitation “varies sinusoidally.” Turning to Lockheed’s contention concerning the DOE, the Federal Circuit noted that under Festo, it must first determine whether the scope of the DOE, as applied to the disputed claim limitation, had been narrowed by prosecution history estoppel before attempting to apply the DOE.

During prosecution of the ‘772 patent, the disputed limitation was amended twice, narrowing the literal scope of the limitation in response to the Examiner’s obviousness rejections. Noting that Festo emphasizes the need for certainty as to the scope of patent protection and that the notice function of patent claims has become paramount, the Federal Circuit held that no scope of equivalents was available to Lockheed under the DOE, despite Lockheed’s arguments for a “flexible bar” approach.