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Court Vacates Preliminary Injunction After Limiting Claims Based on Disclaimer in Specification and Prosecution History

May 29, 2001

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Last Month at the Federal Circuit - June 2001

Judges: Schall (author), Lourie, and Linn

In Transonic Systems, Inc. v. Non-Invasive Medical Technologies Corp., No. 01-1110 (Fed. Cir. May 29, 2001) (nonprecedential decision), the Federal Circuit vacated a preliminary injunction based on an error in a claim construction and remanded the case for further proceedings.

Transonic Systems, Inc. (“Transonic”) had successfully obtained a preliminary injunction against Non-Invasive Medical Technologies Corporation (“NMT”) for alleged infringement of Transonic’s U.S. Patent No. 5,685,989 (“the ‘989 patent”). The ‘989 patent is directed to a method and apparatus for measuring blood flow in hemodialysis shunts.

NMT argued that the district court had misconstrued four limitations of the asserted claims. The Federal Circuit reviewed these limitations, rejected NMT’s argument with regard to two of them, but agreed with the two others. In particular, the Court agreed that the district court had interpreted too broadly limitations concerning the calculation or determination of the rate of patient blood flow in a shunt. The Federal Circuit identified in the specification only a select group of equations for providing the calculation. Moreover, Transonic had argued during the prosecution history that the disclosed equations were critical to achieving the purpose of the invention and were novel over the prior art. Thus, the Court ruled, this intrinsic evidence means that the calculating and determining limitations must be construed as requiring the use of at least one of the equations set forth in the specification. Accordingly, the Court vacated the preliminary injunction and remanded