Guidance on Construing Claim Construction, a.k.a. Diminutive Claim Construction

Addressing the issue of construing language in a claim construction order (language not found in the claims), the U.S. Court of Appeals for the Federal Circuit reversed a finding of non-infringement based on incorrect claim construction. Advanced Fiber Technologies v. J & L Fiber Services, Case No. 11-1243 (Fed. Cir., April 3, 2012) (Lourie J.) (Dyk, J. dissenting-in-part).

The patented technology in this appeal involved screening devices used in the pulp and paper industry. The three independent claims of the asserted patent include the term “screening medium” or its synonym “screening plate.” The district court constructed “screening medium” as a “perforated barrier through which stock is passed to remove oversized, troublesome, and unwanted particles from good fiber.” At AFT’s request the district court also construed the term “perforated,” which appeared in this construction, but did not appear in the claims, as “pierced or punctured with holes.” Based on its construction, the district court granted summary judgment of non-infringement in favor of the defendant. AFT appealed.

On appeal, the Federal Circuit found that the district court incorrectly construed “perforated” and provided guidance on how to conduct what it called “derivative claim construction.” Although the Court noted that it does “not ordinarily construe words that are not in claim,” where such derivative construction of a non-claim term is required, courts must follow the guiding principles set forth in Phillips, namely that the specification informs the proper construction. The Court further instructed that just with any claim construction, the ultimate goal in derivative construction “is determining the meaning and scope of the patent claims asserted to be infringed.”

The Federal Circuit concluded that the district court erroneously construed perforated using extrinsic evidence that contradicted the intrinsic record. Specifically, in construing “perforated,” consistent with dictionary definitions, to mean “pierced or punctured with holes.” The Federal Circuit explained that the district court did not give due weight to the explicit disclosure of an embodiment utilizing a wedgewire screen. The disclosure of wedgewire screens was inconsistent with the district court’s definition because the openings in wedgewire screens are merely gaps between individual wires, and not formed through piercing or puncturing. The Court found that the prosecution history did not show any disclaimer of the wedgewire disclosure and that the correct construction of “perforated” in this context is simply “having holes or openings.”

Judge Dyk file a separate decision dissenting in part with respect to the construction of “screening medium,” “screening plate,” the derivative construction of “perforated” and reversal of summary judgment of non-infringement. Specifically, Judge Dyk found that the prosecution history, in connection with method claim in the patent that recites a method of manufacturing a screen plate, and the understanding of on skilled in the art at the time of the invention, all supported the district court’s construction of “perforate.”