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Proper Claim Construction Leads to No Infringement

May 07, 2004
Burwell, L. Scott

Decision icon Decision

Last Month at the Federal Circuit - June/July 2004

Judges: Clevenger (author), Mayer, and Newman (dissenting)

In Housey Pharmaceuticals, Inc. v. Astrazeneca UK Ltd., No. 03-1193 (Fed. Cir. May 7, 2004), the Federal Circuit affirmed the district court’s final judgment of invalidity and noninfringement of four patents directed to methods of screening for protein inhibitors or activators.

Housey Pharmaceuticals, Inc. (“Housey”) sued Astrazeneca UK Ltd. and several other Defendants, alleging infringement of four patents, all of which are titled “Method of Screening for Protein Inhibitors or Activators.” The patented method is an assay to determine whether a substance is an inhibitor or activator of a particular protein (called a “protein of interest” or “POI”) in a cell. The method employs two cell lines and compares the effect the tested substance has on the phenotypic response to the POI in each cell line.

The district court construed several limitations of the claims, including “inhibitor or activator of a protein,” rejecting Housey’s argument that an “inhibitor or activator of a protein” is limited to substances that directly bind to the POI, and instead adopting a broader construction that includes substances that operate through indirect interactions without necessarily binding to the POI itself. Housey subsequently stipulated that, if the claim construction were not reversed or modified on appeal, its patents would be invalid and not infringed. The district court thus entered final judgment of invalidity and noninfringement.

On appeal, the Federal Circuit upheld the district court’s claim construction. The Federal Circuit noted that the plain language of the representative claim clearly supported the district court’s construction and was inimical to any narrower construction. Although Housey had produced definitions of the terms “inhibitor” and “activator” from technical dictionaries that included a direct-binding limitation, the Federal Circuit noted that the dictionaries also included general definitions of those terms that require only an effect on the biological activity of the protein, regardless of the mechanism used to achieve that effect.

The Federal Circuit also held that the intrinsic evidence did not clearly disavow the broad, plain meaning of the term “inhibitor or activator of a protein,” and further found that the specification and prosecution history affirmatively demonstrated that Housey intended the broader meaning that is not limited to direct binding. The Federal Circuit rejected Housey’s arguments that the specification contemplated only direct binding between the substance being tested and the POI, characterizing them as attempts to import limitations from the specification into the claims.

In dissent, Judge Newman asserted that the majority’s approach to claim construction was based upon “confusing recent pronouncements” of the Court that exalt dictionary definitions over technical context. She argued that the majority had reinforced the recently created dominance of general definitions, and further contended that terms in patent claims should be understood in the technical and scientific context of the specification and should be presumed to have their technical meaning, not a general meaning.