What is reexamination, and when would I use it instead of IPR?

An accused infringer may request ex parte reexamination under 35 U.S.C. 302. The statute permits any person, including the patent owner, to request it. A request identifies the prior art and explains its relevance to the claims; it also requires the prescribed fee.

What starts reexamination?

Under section 303, the Office decides within three months whether the request raises a substantial new question of patentability. Previously considered art can still raise that question. A qualifying question leads to reexamination under sections 304 and 305.

How much can the requester participate?

This is an examination procedure. If the patent owner submits the statement allowed by section 304, a third-party requester may reply within the statutory period. That limited role differs from participation as an IPR petitioner. Under section 305, the owner may propose amendments or new claims but may not broaden the patent claims.

Can it avoid IPR timing or estoppel problems?

Section 302 does not impose the complaint-service deadline found in the IPR statute. But reexamination is not a way around estoppel that already applies: section 315(e)(1) can bar a petitioner or related party from requesting or maintaining an Office proceeding on grounds covered by an IPR final written decision. Evaluate that restriction before choosing another procedure.

Will the court case stop?

A request does not itself secure a district-court stay. The court controls that decision. Murata Machinery USA, Inc. v. Daifuku Co., Ltd. explains the court's discretion to manage its docket, including stays related to Patent Office proceedings. Keep complying with court deadlines unless an order changes them.

What should I compare?

Consider the prior art, available filing windows, requester participation, existing estoppel, and the parallel court schedule. The IPR and stay guides provide related background.