Whether in a new patent application or in an issued patent being subject to a post grant review proceeding, the USPTO utilizes a Broadest Reasonable Interpretation (BRI) standard for all patent claims. Under this one-size-fits-all standard a patent claim is construed consistent with the accompanying patent specification from the perspective of one skilled in the relevant art.
Although applied in post grant proceedings, BRI was developed as an examination expedient for patent examiners to protect the public notice function of newly minted patent claims. That is, since no property rights exist at the time of patent application, a pure BRI analysis properly ignores the developing intrinsic record as a guide to claim meaning (i.e., prosecution history) in favor of claim amendment practices. However, once an issued patent returns to the USPTO for a post grant analysis, consideration of prosecution history as intrinsic evidence is more of a mixed bag—especially when before examiners steeped in traditional BRI practices (e.g., reexamination, reissue, supplemental examination).
Recently, the Court of Appeals for the Federal Circuit (CAFC) has sent the USPTO Patent Trial & Appeal Board (PTAB) seemingly conflicting messages on the use of prosecution history during post grant proceedings.