The US Court of Appeals for the Federal Circuit affirmed a district court's narrow claim construction, finding that the specification and prosecution history of the patent-at-issue contained clear and unequivocal statements that the inventor intended to limit the claim scope. Poly-America, L.P. v. API Industries, Inc., Case No. 16-1200 (Fed. Cir., Oct. 14, 2016) (Reyna, J).

Poly-America owns a patent directed to an improved construction of an elastic drawstring trash bag. The district court, relying on the patent's specification and prosecution history, construed the term "short seal" to mean "[a] seal for securing the elastic drawstring, which seal is located adjacent to a side seal, and that is not substantially aligned with the side seal, but extends inwardly from the interior edge of the side seal." Following claim construction, Poly-America stipulated to non-infringement, and the district court entered final judgment in API's favor. Poly-America appealed, arguing that by construing the term "short seal" to require inward extension, the district court improperly imported limitations from the embodiments described in the specification, misread the prosecution history and ignored principles of claim differentiation.

On appeal, the Federal Circuit reviewed the district court's claim construction de novo because the district court relied solely on intrinsic evidence. The Federal Circuit found that the inventor disavowed trash bags with short seals that do not extend inwardly to narrow the upper opening width in relation to the bag proper width.

The Federal Circuit found that the inventor disavowed claims lacking short seals by emphasizing short seals as a characteristic of the claimed invention in the written description. Additionally, the inventor disavowed claims lacking short seals because the written description states that prior art bags are difficult to secure over trash receptacle lids because of the absence of this feature, which is designed to make it easier to fit the bag around a trash can. Further, the prosecution history demonstrates that Poly-America distinguished its claimed invention from the cited prior art based on the fact that the patent describes bags that extend inwardly to narrow the upper opening width in relation to the bag proper width. Because of the many instances of disavowal, the Federal Circuit found it irrelevant that the terms "bag proper width" and "relaxed upper opening width" are not present in the claim; in light of the written description, it is clear that all of the claimed trash bags must have these features.

The Court explained that the district court's analysis did not improperly import limitations from embodiments described in the written description because every embodiment described in the written description has inwardly extended short seals, and every section of the written description emphasizes the importance of this feature. Further, the Court found that claim differentiation principles cannot be used to broaden claims beyond their meaning in light of the patent as a whole and cannot override clear statements of claim scope found in the specification and prosecution history. 

Disavowal of Claim Scope in a Trash Bag Patent

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