On appeal from a grant of summary judgment and a jury verdict of invalidity, the U.S. Court of Appeals for the Federal Circuit reversed the claim construction of a key disputed term and remanded for reconsideration of validity. Hologic v. SenoRx, Case No. 10-1235 (Fed. Cir., Feb. 24, 2011) (Lourie, J.) (Friedman, J., dubitante).

At issue were two independent claims that generally relate to a balloon catheter for expanding inside the location of a surgically removed tumor, with a radiation source disposed between the balloon and the catheter. The first independent claim required the radiation source to be “asymmetrically located and arranged within the expandable surface.” The second independent claim required “asymmetric placement of a radiation source with respect to a longitudinal axis.”

In the district court, the first independent claim was construed to mean that the radiation source was asymmetric with respect to the balloon surface. The court noted that the specification and claims frequently referred to asymmetry with respect to the longitudinal axis, but concluded that the first claim ought to be construed differently from the second claim, which expressly requires the asymmetry of the radiation source to be with respect to the longitudinal axis. SenoRx was found to infringe only the second independent claim. After the district court subsequently granted SenoRx summary judgment on invalidity, Hologic appealed.

On appeal, the Federal Circuit reversed the claim construction, finding that the intrinsic record of the specification and prosecution history unambiguously required the asymmetry of the radiation source to be with respect to the longitudinal axis. The Federal Circuit noted that “asymmetry is a relative concept that can exist only in relation to some reference” and further noted that the first claim did not clearly specify the reference for the asymmetry of the radiation source. However, citing Phillips, the court explained that “[a]lthough the claims of a patent define the invention to which the patentee is entitled the right to exclude, we must read the claims in view of the specification, of which they are a part.” Hence, the Federal Circuit concluded that the “specification makes clear what the inventors contemplated as their invention.” The Federal Circuit went on to analyze the intrinsic claim construction evidence, resolving the ambiguities identified by the district court as favoring the interpretation of “asymmetry” as referring to the longitudinal axis.

The patentee also argued on appeal that the district court erred in using the language of the second independent claim as a basis for interpreting the first independent claim, because the doctrine of claim differentiation is only appropriate in comparing dependent with independent claims. The Federal Circuit avoided referring to the doctrine of claim differentiation in denying this argument. Rather, the Federal Circuit wrote that “[o]ther claims can be valuable sources of enlightenment as to the meaning of a claim term” and “different terms or phrases in separate claims may be construed to cover the same subject matter” when warranted by the intrinsic record. Thus, while the patentee may have been correct about the scope of the doctrine of claim differentiation, the Federal Circuit strongly embraced the use of surrounding claims (both dependent and independent) in construing disputed terms. The case was remanded.

Judge Friedman’s opinion dubitante (indicating doubt not rising to the level of dissent) simply stated that the majority had, in effect, read a limitation from the specification into the first claim, a limitation that the patentee had expressly included in the second claim but not the first claim. Thus, Judge Friedman would have found that the district court correctly construed the first claim.

Practice Note: In drafting independent claims of varying scope, ensure that the specification provides adequate support for each different embodiment claimed. Broader independent claims may otherwise be limited to the scope of narrower dependent or independent claims.