In Advanced Fiber Technologies Trust v. J & L Fiber Services, Inc., the Federal Circuit reversed the district court’s claim construction that relied on extrinsic evidence and was inconsistent with the specification. Although the patent holder ultimately may prevail, a different claim strategy might have avoided the problematic claim construction.

The Patents At Issue

The patents at issue were AFT’s U.S. Patent 5,200,072, reissued as RE39,940. The Federal Circuit described the invention as follows:

The patented technology in this appeal involves screening devices used in the pulp and paper industry. . . . The screening may be accomplished using a flat or cylindrical screen containing openings. According to the specification of asserted U.S. Patent RE39,940 . . . a persistent problem in the screening process is clogging of the openings in the screen resulting in reduced screening efficiency. The ’940 patent purports to address this problem with specially designed screening devices that offer substantially increased efficiency and flow capacity, among other beneficial characteristics.

 Representative apparatus claim 1 recites in part:

1. A screen cylinder comprising:
a generally cylindrical screening medium having a plurality of openings therethrough;
. . .
the openings in said screening medium being elongated and extending in a generally axial direction substantially normal to the circumferential extent of said recesses.

 Representative method claim 18 recites in part: 

18. A method of manufacturing a screen for use in screening for pulp, said screen being formed of a screening plate and a backing plate, said screening plate having first and second opposite faces, comprising the steps of . . .

The Claim Construction Issues

The claim construction issues centered around the term “screening medium” in apparatus claims 1 and 10 and the term “screening plate” in claim 18.

The Prosecution History

During examination of the reissue application the claims were rejected as anticipated by U.S. Patent 4,276,265 to Gillespie. As characterized by the Federal Circuit, “Gillespie discloses ‘screens for use in process flow stream applications,’ such as a ‘radial flow catalytic reactor.’”  In making the rejection, the Patent Office examiner stated, “Although Gillespie is not directed to a pulp fiber sorting application, . . . [s]tructurally, applicant’s claimed screen device is indistinguishable from Gillespie’s screen.”

In response, AFT emphasized the field of the invention—the pulp treatment art—and explained that “certain claim terms ‘are terms of the pulp treatment art.’” In support of its position, AFT provided definitions from the Handbook of Pulp and Paper Technology:

SCREEN: Separation device utilizing some type of perforated barrier for removing unwanted material from a stock stream.

SCREENING: Process step involving passage of stock through some form of perforated barrier to remove oversize, troublesome and unwanted particles from good fiber.

SCREEN PLATE: Perforated metal plate utilized on many designs of pulp screening equipment that impedes pulp flow and is instrumental in causing a separation between suspended particles on the basis of their size, shape, and/or flexibility.

AFT also contrasted the slot width of the Gillespie apparatus with that used for screening pulp fibers, stating:

“[P]ulp fibers have diameter less than 50 microns (0.050 mm) and typically slot widths of 0.2 mm would be used for aspects of the invention. In contrast, the Gillespie screen slots are 0.030 inches, that is, 0.762 mm. The slots of Gillespie are over three times the size of the slot width of the present invention.”

These arguments overcame the rejection based on Gillespie.

The District Court’s Claim Construction

The district court cited the prosecution history and relied on the definition of “screening” from the Handbook of Pulp and Paper Technology, and so construed “screening medium” as “a perforated barrier through which stock is passed to remove oversized, troublesome, and unwanted particles from good fiber.”

The district court also construed the term “perforated” by referring to “general and technical dictionary definitions of ‘perforate’ and ‘perforation,’” and arriving at the definition “pierced or punctured with holes.” In so doing, the district court “observed that this construction conformed to the patent’s written description with the exception of  ‘a one-sentence mention that “a wedgewire screening plate may be used.”‘” The district court noted that “none of the claims explicitly recites a wedgewire screen—that is, a screen made by assembling closely spaced parallel wires, not by piercing or puncturing.”

The district court also construed the claim terms “openings” and “slots”  in claims 1 and 10. Although the patent describes these terms broadly, the district court found “an unmistakable disavowal of the full scope of these terms” to arise from the arguments made to overcome Gillespie.  The court cited that prosecution history as limiting slots or openings to those “having widths less than one-third of 0.762 mm,” i.e., “less than 0.254 mm.”

The district court granted summary judgment of non-infringement based on this claim construction, and AFT appealed.

The Federal Circuit’s Claim Construction

On appeal, the Federal Circuit agreed that the district court was right to rely on the definitions provided during prosecution of the ‘940 patent, such that “screening medium” was correctly defined as a barrier that is “perforated.” However, the Federal Circuit found that the district court had gone too far by relying “solely on dictionary definitions” to interpret “perforated,” particularly where that extrinsic evidence “contradicted the patent’s specification, including the claims and written description.”

For example, the Federal Circuit noted that “[t]he claims themselves do not require the screening medium to be made by puncturing or piercing, they simply limit the screening medium to ‘having a plurality of openings therethrough.’” While much of the specification is similarly open, one disclosed embodiment requires a definition broader than that adopted by the district court, because it related to a “wedgewire screening plate,” which is “made by assembling wires, not by puncturing or piercing.” For this reason, the Federal Circuit “reject[ed] the district court’s construction of ‘perforated’ in view of intrinsic evidence providing for a screening medium formed by means other than piercing or puncturing.”

The Federal Circuit agreed with the district court’s definition of “slots” and “openings.” The Federal Circuit noted that the prosecution history statements at issue were “urged in support of patentability,” “so clear as to show reasonable clarity and deliberateness” and “so unmistakable as to be unambiguous evidence of disclaimer.”

Still, having disagreed with the district court on one claim construction issue, the Federal Circuit reversed the summary judgment of non-infringement and remanded for further proceedings.

Judge Dyk’s Dissent

Judge Dyk dissented from the Federal Circuit decision, based on his determination that the intrinsic evidence supported the districut court’s construction of “perforated.” In particular, Judge Dyk noted that the Gillespie reference disclosed a wedgewire apparatus, and that AFT overcame the rejection based on Gillespie by emphasizing that “screening medium” and “screening plate” are terms of art in the pulp treatment industry, and by citing dictionary definitions from the Handbook of Pulp & Paper Terminology, which Judge Dyk read as defining a “perforated plate” as one with “holes . . . made by punching, drilling, or some other similar method of creating a hole through an otherwise solid object.”

With regard to the wedgewrie embodiment disclosed in the application, Judge Dyk noted:

Not every embodiment disclosed in the specification necessarily falls within the scope of the claims

Avoiding The Claim Construction Issue

Although AFT prevailed on its claim construction argument, Judge Dyk’s dissent indicates that its victory was no sure thing. AFT’s case might have been clearer if any claims were specifically directed to the wedgewire embodiment. Thus, this case serves as a reminder of the potential benefit of a robust claim set, not just to protect different aspects of the invention, but also to help guide construction of broader, generic claims.