Biofer S.P.A. v. Vifor (International) AG
Panel: Dyk, Linn, Reyna
The Federal Circuit affirmed a judgment of noninfringement in favor of Vifor (International) AG based on claim construction of U.S. Patent No. 8,759,320, which relates to a process for manufacturing iron-sugar complexes used to treat iron deficiency. The dispositive issue was whether claim 1's recitation of "pH between 7.0 and 9.0" required maintaining that pH throughout the oxidation reaction step, or merely that the pH fall within that range at some point during the process. After Biofer's discovery confirmed Vifor's process operated within the claimed pH range for only approximately 90% of the reaction, the parties stipulated to noninfringement under the district court's construction, with Biofer expressly preserving appeal of the claim construction ruling.
The court's de novo analysis illustrates how specification-based claim construction can incorporate functional requirements not explicit in numerical range terms. Relying on repeated use of "maintain" in the specification's description of the oxidation step and the prosecution history—where the patentee submitted a declaration corroborating the criticality of maintaining pH within the claimed range to avoid depolymerization—the court concluded that the broader pH range disclosed in the specification (5.0 to 12.0) was not improperly disclaimed by construing the narrower claimed range (7.0 to 9.0) as requiring maintenance throughout the reaction. The court rejected Biofer's attempt on appeal to advance a "brief excursions" theory, finding it forfeited where Biofer had argued below that even a millisecond within range would suffice.