CAFC Refuses To Find Estoppel Based On Arguments Before The EPO

Tap Pharmaceutical v. OWL Pharmaceuticals (Fed. Cir. 2005).

In an action for infringement of several pharmaceutical patents, the Federal Circuit upheld the district court’s findings that the generic drug-maker (OWL) had infringed two of the plaintiffs’ (Tap et al) patents.

Broad Scope Derived from Specification: Claims which described the patented compound as “comprising a copolymer … of lactic acid and … of glycolic acid” were interpreted by the appellate panel to also encompass copolymers “produced by any method.”  Although the specification only provided examples of copolymers made from lactic and glycolic acid, it did note that the polymer “may be produced by any method.” 

Disclaimer Based On Foreign Prosecution: Regarding foreign prosecution history, the CAFC gave little weight to statements made by the patentee to an Examiner in the European Patent Office that the invention did not include compounds made from lactide or glycolide.  The European Examiner had rejected the claims after this argument was made, finding that the compounds which the patentee had attempted to disclaim were not different from those made from lactic and glycolic acid.  Therefore, because the European claims were later allowed on other grounds, and because the patentee had not made this argument before the USPTO, the patentee must have “receded from that characterization of the claims,” and thus these statements should be given little weight in the process of claim construction.

Even Common Words Construed According To Specification: A second claim directed to “particles containing a water-soluble drug” was interpreted to encompass only particles which included both 1) the drug substance, and 2) a drug-retaining substance, because the drug-retaining substance was included in all the examples in the specification and was listed as a benefit of the invention.  The court held that the term “containing,” while not a technical term, helped to describe the patented technology and therefore “cannot be defined by some ordinary meaning isolated from the proper context.”  Thus, the district court was correct to look to both intrinsic and extrinsic evidence to properly interpret the claim.

The Federal Circuit thus affirmed the district court’s claim construction as to both patents.

NOTE: This post was written by Rebecca Brown.  Ms. Brown is a law clerk at MBHB and a student at Northwestern University School of Law.

• As Attorney Jason Rantanen pointed out in a recent e-mail, there is a clear distinction between the prosecution history disclaimer and prosecution history estoppel.  The disclaimer doctrine is related to “claim construction for the purposes of literal infringement” while the estoppel doctrine bars the assertion of DOE under Festo.