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Glass Half Empty: Patent Reciting “Half Liquid” Is Indefinite

The US Court of Appeals for the Federal Circuit affirmed the district court’s finding that the asserted patent claims were invalid as indefinite because the meaning of the term “half-liquid” was not reasonably clear from the record. IBSA Institut Biochimique, S.A. v. Teva Pharms. USA, Inc., Case No. 19-2400 (Fed. Cir. July 31, 2020) (Prost, C.J.).

IBSA owns a patent directed to pharmaceutical formulations for thyroid hormones that enable a safe and stable oral administration. IBSA listed in the Orange Book the patent for Tirosint®, a soft gel capsule formulation containing the active ingredient levothyroxine sodium. Teva filed an abbreviated new drug application to market a generic version of Tirosint®, and IBSA responded by filing a lawsuit for patent infringement against Teva.

During claim construction, the parties disputed the construction of the term “half-liquid.” IBSA proposed that “half-liquid” should be construed to mean “semi-liquid,” while Teva argued that the term was indefinite or should be construed as “a non-solid, non-paste, non-gel, non-slurry, non-gas substance.” The district court began its analysis by acknowledging that the parties “agree that the intrinsic record does not define ‘half-liquid.’” IBSA argued that a priority Italian patent application’s use of the word “semiliquido” (translation: semi-liquid) in the same places where “half-liquid” was used in the patent at issue supported its position that the two terms were synonyms. The district court disagreed, noting several differences in the two patents that indicated that the different choice of terms was intentional. Further, the district court noted that the applicant originally used the term “semi-liquid” in a dependent claim during prosecution, but later removed this term, indicating that the applicant understood the terms to be different and intentionally chose not to use “semi-liquid” in the asserted claims. The district court also found IBSA’s extrinsic evidence (e.g., reliance on dictionary definitions, other patents and expert testimony) unpersuasive. The district court accordingly found the asserted patent claims invalid as indefinite because the meaning of “half-liquid” was not reasonably ascertainable from the record. IBSA appealed.

The Federal Circuit affirmed. The Court first found that the intrinsic record failed to establish the boundaries of the term “half-liquid.” The Court agreed with the district court’s analysis, finding that neither the claims nor the specification supported IBSA’s proposed construction. The Court also explained that the prosecution history reinforced the conclusion that the applicant understood “half-liquid” to be different from “semi-liquid,” because the applicant intentionally removed the term “semi-liquid” in a dependent claim during prosecution. The Court disagreed with IBSA’s suggestion that the district court refused to consider the foreign Italian priority document—rather, “when discrepancies between a foreign priority document and the U.S. filing exist, it may be proper to view the discrepancies as intentional.”

Turning to the extrinsic record, the Federal Circuit found that the district court did not clearly err in its analysis of the presented dictionary definitions, other patents and expert testimony. The Court noted that IBSA identified no scientific dictionaries containing the term despite IBSA’s argument that “half-liquid” would be a recognizable term of art. The Federal Circuit also found that the four other patents IBSA cited used the term “half-liquid” in different contexts than the asserted patent. Finally, the Court found that expert testimony demonstrated that “half-liquid” was not a well-known term in the art and a person of ordinary skill in the art would face difficulty in ascertaining the boundaries of a “half-liquid.”

© 2020 McDermott Will & EmeryNational Law Review, Volume X, Number 226


About this Author

Mandy H. Kim, McDermott Will Emery Law firm, Intellectual Property Litigation

Mandy Kim is an associate with the law firm of McDermott Will & Emery LLP and is based in the Firm’s Orange County office.  She focuses her practice on intellectual property litigation.