The doctrine of estoppel may only be applied in limited situations such as supplement, amendment, correction, response and reply, which are related to patentability and narrowing of the scope of claims. “Related to patentability” may include the elements in order to overcome the challenges of prior art and others like enablement, written description requirement, et al. Whether the requirement of “related to patentability” is met should rely on the reason which is presented by the patentee when submitting supplement, amendment, orrection, or response in the application process. If the reason is not specific, presume that it is related to patentability. However, if the patentee could prove that it doesn’t relate to patentability, then the element is not applicable to the doctrine of estoppel. In addition, if the supplement, amendment, correction, response and reply submitted by the patentee does not narrow the scope of claims, the doctrine of estoppel would not be applicable, even if the submission is related to patentability. Furthermore, the scope prevented by the doctrine of estoppel is only limited to the part restricted or excluded by the patentee, but it does not mean that the arguments of doctrine of equivalents can not be raised regarding the other part of the claim. The purpose is to protect the scope of equivalents regarding the patent, and to prevent the scope of the claims abandoned by the patentee from being wrongfully judged. However, the patentee should carry the burden of proof that the amended part was not excluded from the scope of equivalents. (e.g., the scope of equivalents such as novel techniques which could not be foreseen during the process of the supplement, amendment, correction, response and reply; the limited relevance between the scope of equivalents and the reasons of supplement, amendment, correction, response and reply; no reasonable expectations that the patentee might record the scope of equivalents at that time. )

Estoppel