Should Estoppel Stop You From Requesting Inter Partes Reexamination?
By Robert A. Saltzberg, Kaare D. Larson, and Benno M. Guggenheimer Inter partes reexamination offers an attractive supplement (or even alternative) to litigation for challenging the validity of a patent. Unlike ex parte reexamination, inter partes reexamination advantageously enables a third party requester to participate in the prosecution, including any appeal. Inter partes reexamination, however, is not without its risks. The estoppel aspect of the procedure is “the most frequently identified inequity that deters third parties from filing requests for inter partes reexamination of patents.” Specifically, under 35 U.S.C. ยง 315(c), a third party requester may be estopped in litigation from challenging patent claims on invalidity grounds that were or could have been raised in the course of an inter partes reexamination. Accordingly, as part of the decision to file an inter partes reexam, a party should carefully consider potential estoppels that could attach in a later district court p
