In an opinion addressing prosecution history estoppel, the US Court of Appeals for the Federal Circuit affirmed a district court’s decision granting summary judgment of non-infringement, finding that the patentee was estopped from including certain subject matter within the scope of an asserted claim when other claims directed to that subject matter had been canceled during prosecution. UCB, Inc. v. Yeda Research and Development Co., Ltd., Case No. 15-1957 (Fed. Cir., Sept. 8, 2016) (Newman, J).

UCB sued Yeda in district court, seeking declaratory judgment as to non-infringement and invalidity of a patent with claims directed to a monoclonal antibody. The question was whether the scope of the asserted claim included chimeric and humanized antibodies, or only murine (mouse) antibodies, the latter being the only antibodies described in the specification. Yeda argued that humanized and chimeric antibodies should be included because they were known in the art as of the filing date. UCB responded that the prosecution history prohibited such broad coverage. Specifically, during the lengthy prosecution, Yeda limited the original claims to only murine antibodies and then added a new claim without this limitation. That claim was rejected for lack of enablement. In response, Yeda argued that chimeric and humanized antibodies were contemplated, and submitted a declaration that it was within the level of skill in the art to produce such antibodies at the filing date. Yeda also added new claims specifically claiming chimeric and humanized antibodies. The Examiner withdrew the rejection for lack of enablement against the first new claim but rejected the additional new claims as adding new matter. Yeda then canceled the additional claims, and the patent issued with the first new claim. 

At trial, the district court granted UCB’s motion for summary judgment of non-infringement, finding that the prosecution history prohibited construction of the claim to include chimeric and humanized antibodies. According to the district court, because Yeda had withdrawn rejected claims that included the subject matter at issue to obtain issuance, it could not now recover the surrendered claim scope. Yeda appealed.

The Federal Circuit affirmed the district court’s construction, finding that Yeda was estopped from including chimeric and humanized antibodies within the scope of the claim. The Federal Circuit pointed out that actions and arguments made during prosecution must be considered when construing the claim. Yeda argued that the issued claim itself had never been narrowed and therefore no prosecution history estoppel should apply to that claim. The Federal Circuit rejected this position, stating, “[T]he general rule is that a patent applicant cannot later obtain scope that was requested during prosecution, rejected by the Examiner, and then withdrawn by the applicant.”