Stated Purpose of Invention May Limit Claim Scope

KAKEN PHARMCEUTICAL CO., LTD., BAUSCH HEALTH COMPLAINTS INC., V. ANDREI IANCU, UNDER SECRETARY OF COMMERCE FOR INTELLECTUAL PROPERTY AND DIRECTOR OF THE UNITED STATES PATENT AND TRADE MARK OFFICE

Judges: Newman, O’Malley, and Taranto. Appeal from the Patent Trial and Appeal Board

Summary: A statement of purpose in the specification and statements made to overcome a rejection during prosecution may justify a narrow claim construction.

The Patent Trial and Appeal Board found Kaken Pharmaceutical Co.’s and Bausch Health Companies Inc.’s (“Kaken”), patent to be obvious in an IPR filed by Acrux Limited and Acrux DDS Pty. Ltd (“Acrux”).  Kaken’s claims were directed to a topical cream used to treat finger/toe nail infections. In reaching its conclusion, the Board relied on a broad definition of “nail” in the specification to construe the claims as pertaining to topical treatment of an infection both in and around the nail. Based on this interpretation, the Board found Kaken’s patent invalid after accepting numerous prior art references involving the use of Kaken’s same active ingredient to treat infections on the surface of the skin.

The Federal Circuit found the Board’s claim construction to be overbroad. While Kaken’s specification did include a broad definition of “nail,” additional factors indicated that the broadest reasonable interpretation for the area of infection treated by Kaken’s product is limited to the “nail plate.” Noting that a patent’s statement of the invention’s purpose informs the proper construction of a claim, the Court relied on several passages of the specification that indicated the patent was limited to treatment of infections of the “nail plate.” Additionally, statements made by Kaken and the examiner during prosecution clarified that the claims were limited to treatment of an infection of the “nail plate.” Because the Board’s obviousness determination was based in part on its erroneous claim construction, the Federal Circuit vacated the Board’s final written decision and remanded to the Board.

Editor: Paul Stewart

Written by: Matthew Friedrichs & Andrea Cheek