United States: Federal Circuit Imposes Plain Meaning Construction on Claim

The U.S. Court of Appeals for the Federal Circuit has held that a process for the production of ethylene oxide using a catalyst "characterizable" by a mathematical efficiency equation could be infringed by a process using the same catalyst produced in a different manner. Union Carbide Chemicals & Plastics Technology Corp. v. Shell Oil Co., Case Nos. 02-1001, -1020 (Fed. Cir. Sept. 20, 2002).

This case involves technology to improve silver catalysts for the production of ethylene oxide, a chemical used to make substances such as polyester fiber, resin and film and is produced when ethylene is reacted with oxygen. The catalyst may be improved by the addition of other metals to increase the efficiency of the reaction and to prolong the catalyst’s duration. The claim recited that certain constituents in the catalyst are "characterizable by [a recited] efficiency equation."

The district court construed the claim limitation of a catalyst "characterizable by an efficiency equation" to mean a catalyst "determined from" the recited equation. The district court acknowledged that this construction represented a departure from the plain meaning. Based upon that claim construction, a jury determined that there was no infringement.

The Federal Circuit reversed, finding that the plain meaning of "characterizable," which is "capable of being described by an efficiency equation," is the correct interpretation. The Federal Circuit examined the intrinsic evidence of record and found that it did not clearly set forth or clearly redefine the claim language so as to put one reasonably skilled in the art on notice that the patentee intended to redefine the plain meaning of the claim term, and that neither the specification nor the prosecution history justified the district court’s departure from the ordinary meaning. Since both the jury verdict of non-infringement the district court’s judgment on the asserted invalidity defenses were based on an erroneous claim construction, the Federal Circuit reversed and remanded the case for a determination in accordance with the correct claim construction.