Part 1: Prosecution History In Claim Interpretation

In the U.S., a prosecution history of a patent (i.e., the proceedings between the patent applicant and the USPTO from application filing to patent issuance) comes into play in the context of claim construction (for example, before a district court, before the PTAB in a post-grant proceeding, or in the eyes of a third party analyzing the patent for freedom to operate reasons), and also in the context of an assessment of infringement under the doctrine of equivalents. The Federal Circuit has recognized distinct roles of the prosecution history in claim construction and infringement under the doctrine of equivalents:

There is a clear line of distinction between using the . . . prosecution history to reach an understanding about disputed claim language and the doctrine of prosecution history estoppel which estops, or limits later expansion of the protection accorded by the claim . . . under the doctrine of equivalents when the claims have been purposefully amended