Reversing two district court opinions, the U.S. Court of Appeals for the Federal Circuit again emphasized that it will not limit claim terms by the specification and that prosecution history must be unambiguous to be limiting. Inverness Medical Switzerland GmbH v. Warner Lambert Co., Case Nos. 01-1147, -1177 (Oct. 31, 2002); Inverness Medical Switzerland GmbH v. Princeton Biomeditech Corp., Case No. 01-118 (Oct. 31, 2002).
In separate filings at the same district court (U.S. District Court for New Jersey), Inverness sued Warner Lambert and Princeton for infringement of three patents, all directed toward a pregnancy-testing device using a strip of porous material facilitating a chemical reaction between a reagent, proteins found in urine and a colored label. After the district court granted each of the defendants’ summary judgment of non-infringement, Inverness appealed. In separate opinions, the Federal Circuit vacated the judgments.
In Princeton, the summary judgment of non-infringement was based on the district court’s construction of claim limitation "wherein mobility of said labeled reagent within said test strip is facilitated by … a material comprising a sugar" to require a sugar that improved mobility of the reagent at the point of its release from the test strip (i.e., when the reagent comes into contact with urine), which did not occur in the Princeton product. Inverness argued on appeal that the facilitation of mobility could occur either at the time of release or during subsequent transit of the reagent.
Based on the dictionary definition and the discussion in the patents, the Federal Circuit found that "mobility" of the reagent referred to both the point-of-release from the test strip as well as post-release, and the use of the term "mobility" in other claims contradicted Princeton’s construction.
In the Warner Lambert appeal, the same argument was presented regarding the term "mobility." Warner Lambert also argued that the claim limitations "said labeled reagent is dry on said test strip" and "drying said labeled reagent onto a portion of said test strip" required surface disposition of the reagent, which was not present in its product. Inverness argued that the phrases "on" and "onto" should be more broadly construed to include disposition of the labeled reagent within the test strip.
The Federal Circuit noted the dictionary definitions of "on" and "onto" were identical and, unless limited by the specification or prosecution history, could refer to either a surface location or a presence within the test strip: "a word that has an ordinary meaning encompassing two relevant alternatives may be construed to encompass both alternatives." The Court then looked to the specification, which only discussed a surface application of the reagent, but found this to only be a preferred embodiment that did not preclude the claims from encompassing a test strip containing the reagent within its inner layers. Next, the Court addressed the prosecution history of the patents. Warner Lambert argued that Inverness had amended its claims using the "on/onto" language in response to the examiner’s finding that that scope of enablement was limited to surface application of the labeled reagent. Inverness argued that the examiner also had invited it to show that the prior art recognized alternative means, other than surface application, of providing mobilization. The Federal Circuit acknowledged that "failure to object to an examiner’s interpretation of a claim ordinarily disclaims a broader interpretation" but found that was not the case here. Rather, the Federal Circuit found that it was not clear from the prosecution history whether the patentee had foreclosed the broader dictionary definition (which encompassed both surface application and internal positioning of sugar) in response to the examiner’s rejection. Thus, the Court stated that it would be "inappropriate to limit broad definition of a claim term based on prosecution history that is itself ambiguous."
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