Reexam

Reexam, short for reexamination, is a procedure in United States patent law in which a granted patent is reviewed to determine whether the claims remain patentable in light of prior art. The process is administered by the USPTO and is designed to improve patent quality and potentially resolve disputes without resorting to full litigation.

There are two main forms of reexamination: ex parte reexamination and inter partes reexamination. In ex parte reexamination, a request can be filed by the patent owner or a third party, but only the examiner and the patent owner participate in the proceedings; third parties do not. In inter partes reexamination, which was created to allow third-party participation, interested parties can present evidence and be involved in the process. The grounds for reexamination are based on prior patents or printed publications that raise a substantial new question of patentability about the claimed invention.

The procedure generally involves a petition, an examination by the USPTO to determine whether a substantial new question of patentability exists, and subsequent actions such as office actions, response by the patent owner or requester, and potential amendments to the claims or cancellation of claims. The result is typically documented in an Office action and, if necessary, a reexamination certificate reflecting any amendments or cancellations.

Outcomes of reexamination can range from maintaining the original claims to amending them or canceling certain claims. A reexamination can affect a patent’s enforceability and is often used as a mechanism to correct or clarify patent scope without proceeding to court litigation. The procedure remains an alternative route for evaluating patent validity and limiting unwarranted claim breadth.