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Claim Differentiation Improperly Used to Construe a Claim Term Too Broadly Inconsistent with the Specification and Context of the Invention

February 15, 2006

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Last Month at the Federal Circuit - March 2006

Judges: Rader (author), Friedman, Dyk

In Curtiss-Wright Flow Control Corp. v. Velan, Inc., No. 05-1373 (Fed. Cir. Feb. 15, 2006), the Federal Circuit vacated the district court’s grant of a preliminary injunction in favor of Curtiss-Wright Flow Control Corporation (“Curtiss-Wright”) and remanded the case back to the district court.

The relevant patent, U.S. Patent No. 6,565,714 (“the ’714 patent”), describes a coking drum with a de-heading system. In a process called delayed coking, refineries use coking drums to extract valuable products from heavy residual oil that remains after the refining process. After filling the coke drum with hot residualoil, workers perform the dangerous task of de-heading the drums, which involves manually removing large metal plates known as “heads” that seal the drum’s openings in order to remove the solid coke from the drum. The ’714 patent claims a system and method that de-heads the coke drum without manually removing the heads. The system uses a “de-header valve” with an adjustment mechanism that adjusts the valve during operation of the de-header system.

Curtiss-Wright sought a preliminary injunction against Velan, Inc. (“Velan”) to prevent the launch of a valve that Curtiss-Wright believed infringed claims 14, 33, and 36 of the ’714 patent. Velan’s valves do not include adjustment mechanisms like those disclosed in the ’714 patent. Instead, Velan’s valves contain internal biasing springs that an operator must replace in order to perform a similar type of adjustment. Such replacement requires removing the valve from the coke drum.

Claim 14 of the ’714 patent recites a de-header valve comprising an adjustable dynamic seat. The district court concluded that “adjustable” means that the bias force can be changed in a manner that is “not limited by any time, place, manner, or means of adjustment.” In reaching this construction, the district court relied on the term’s ordinary meaning and the doctrine of claim differentiation. Specifically, the court determined that a narrower construction of “adjustable” would be inconsistent with other claims in the ’714 patent, which recite an adjustment mechanism that allows adjustment while the device is in use or operation. Given this broad interpretation of “adjustable,” the district court concluded that Velan can “adjust” the bias force by replacing the springs in its de-header valve and thus granted the preliminary injunction.

The Federal Circuit vacated the preliminary injunction, concluding that the district court’s reasoning placed too much emphasis on the ordinary meaning of “adjustable” without adequate grounding of that term within the context of the specification of the ’714 patent. The Court noted that the ’714 patent associates the adjustability with a critical aspect of the invention: the ability to de-head the coke drum without having to remove the head unit. Moreover, the patent consistently, and without exception, describes adjustment that occurs during operation of the de-header system and without removal of the head unit. The Court thus concluded that the district court’s construction of “adjustable,” which includes a structure that requires dismantling of the valve to perform the adjustment, found no support in the overall context of the ’714 patent specification. The Federal Circuit also explained that the district court’s reliance on the doctrine of claim differentiation was misplaced. The Court noted two considerations that generally govern the use of claim differentiation when applied to two independent claims: “(1) claim differentiation takes on relevance in the context of a claim construction that would render additional, or different, language in another independent claim superfluous; and (2) claim differentiation ‘can not broaden claims beyond their correct scope.’” Slip op. at 12. The Court concluded that both considerations weighed against the district court’s construction of “adjustable.”

According to the Court, construing “adjustable” to mean adjustable “on the fly” during de-heading did not render the recitation of an adjustment mechanism in other claimssuperfluous. Moreover, the Court noted that in-use adjustability did not necessarily mean the same thing as the presence of an adjustment mechanism. The Court also pointed out that the district court’s broad definition of “adjustable” provided no meaningful limit on claim 14 because any mechanical device would be adjustable under that definition. Lastly, the Court reiterated that the district court’s definition of “adjustable,” based on its claim differentiation analysis, contradicted the context of the invention as described in the specification, which stresses that the invention is “adjustable” during de-heading.