Which Dictionary Definitions Controls in Claim Construction?

The U.S. Court of Appeals for the Federal Circuit, in the course of applying the dictionary driven plain meaning rule, revealed internal disagreement on the proper application of dictionary definitions to claim construction when the dictionary provides competing meanings. Nystrom v. Trex Company, Inc., Case No. 03-1092 (Fed. Cir. June 28, 2004) (Linn, J.) (Gajarsa, J., dissenting in part).

Nystrom, an individual, sued Trex, a manufacturer of exterior decking planks, for the infringement of certain claims directed to a specially shaped board used in the construction of patios and decks. At issue in the case was the construction of the term "board." The district court construed "board" to mean only boards made of wood. The district court based its construction on the specification, which was limited to wood boards, and on arguments made in the prosecution history, which distinguished over the prior art, which did not concern wood flooring. The district court, on summary judgment, then