The U.S. Court of Appeals for the Federal Circuit reversed the district court’s claim construction, noting that arguments made during the prosecution considered with the understanding of a person of ordinary mechanical skill will trump the plain meaning of a claim term. Harvey D. Gillespie v. Dywidag Systems International, USA, Case No. 06-1382 (Fed. Cir., September 6, 2007) (Newman, J.).

Gillespie sued Dywidag for infringement of its patents directed to a mine roof bolt used for reinforcing and supporting the rock formation above a mine roof. Dywidag conceded the presence of all claim elements in the accused device except the element of a “drive collar … having an outer surface defining a drive head that accepts a driving mechanism for rotating [the bolt].” The figures in the Gillespie patents show a drive collar shaped like a hexagonal nut surrounding the bolt. Because of its shape, the drive collar can be grasped and turned from the outside. In contrast, the bolt head of the Dywidag structure contains a square, recessed key socket. A device may be inserted into the socket for the purpose of turning the bolt. The outer surface of the bolt head is cylindrical and thus difficult to grasp and turn.

Dywidag argued that its structure for accepting a driving mechanism was located on the inner surface of the bolt head or collar, rather than the outer surface. However, the district court ruled that the term “outer surface” in the claims does not mean only the exterior surface of the drive head but also included surfaces exterior to an inner portion of the bolt. Dywidag appealed.

The Federal Circuit found that a person of ordinary mechanical skill would not construe the term “outer surface” of the drive collar to include a collar whose interior, not exterior, accepts the drive tool. Although the surface need not be hexagonal, it must be outer with respect to the collar. Furthermore, the Federal Circuit found that Gillespie, as patent applicant, used this same meaning of “outer surface” when he distinguished a prior art reference during prosecution, arguing that the prior art reference “appears to be cylindrical on the outside, thus impractical for being rotated by a mine roof bolting machine.” The Court found that when making this argument, Gillespie clearly used the “outer” to refer to the outside surface of the bolt head. Although Gillespie argued that the distinction was not material to the grant of the patent, the Federal Circuit nevertheless held that Gillespie should be held to what he declared the term “outer surface” meant during the prosecution of the patent.