Article BySusan T. Evans

McDermott Will & EmeryIP Update

Biotech, Food, DrugCivil ProcedureIntellectual PropertyHealth Law & Managed CareLitigation / Trial PracticeAdministrative & RegulatoryFederal Circuit / U.S. Court of Spec.Jurisdiction

Claim Term Can Have Different ConstructionsDepending Upon Context In Patent Claims

Friday, June 28, 2013

Addressing claim construction of a term used in severaldifferent contexts in the asserted patent claims, theU.S. Court of Appeals for the Federal Circuit reverseda stipulated non-infringement judgment entered by adistrict court after claim construction and explainedthat the term in dispute (“substantially pure”) could have different constructions depending upon how theterm is used within the claims andspecification. Aventis Pharmaceutical Inc. v. AminoChemicals Ltd., Case Nos. 11-1335, -1336 (Fed. Cir.,May 20, 2013) (Reyna, J.) (Bryson, J., dissenting).

The patent at issue concerns methods for making purerforms of piperidine derivatives, which are useful asantihistamines, and covers a method used to producefexofenadine, the active ingredient in the allergymedicine Allegra®. The patent is assigned to AlbanyMolecular Research and exclusively licensed byAventis. The defendants in the case, including AminoChemicals, Dipharma, Mylan and Teva, are generic drugmanufacturers. At issue was the meaning of the phrase“substantially pure” recited in the claims tocharacterize an intermediate compound formed during theprocess. The claims include the step of providing a“substantially pure regioisomer” of a particularstructural formula, and then converting the substantially pure regioisomer to a piperidinederivative product. The term “substantially pure” is not defined in the specification, and thespecification fails to attach a numeric value to the substantially pure regioisomer.

The district court concluded that since the patent specification used the phrase “substantiallypure” to describe both the regioisomer intermediate as well as the piperidine end product, itsmeaning must apply equally to both compounds. In its construction, the district court relied uponstatements in the prosecution history (of both the patent and a related patent) which indicated theinventor’s understanding of the term “substantially pure” to equate to a purity of 98 percent, i.e.,pharmaceutical-grade purity with respect to all impurities. Aventis appealed.

The Federal Circuit reversed, explaining that claims must be construed in light of the appropriatecontext in which the claim term is used. The Federal Circuit noted that the district court’sconstruction conflated the purity required for the final product (i.e., for human consumption) withthat of the piperidine intermediate. The Court further found that the “one construction throughoutthe patent” rule adopted by the district court was incorrect, stating that “there is no requirementthat a claim term be construed uniformly, particularly if it would lead to a “nonsensical reading”. The Court further reasoned that the district court improperly decoupled “substantially pure” from“regioisomer” in its construction, recognizing that there was no justification for applying apharmaceutical-grade purity requirement of an ingested end product to an intermediate formed in theprocess. Finally, in turning to the meaning of “substantially pure” in reference to theintermediate, the Court adopted the term’s ordinary and customary definition, citing cases in which“substantially” was interpreted as a non-specific term of approximation that avoids a numerical

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Source URL: http://www.natlawreview.com/article/claim-term-can-have-different-constructions-depending-upon-context-patent-claims

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