Ex Parte Reexamination

By Eugene T. Perez

Reexamination is a statutory procedure that permits the USPTO to reconsider the patentability of the claims in an issued patent in view of prior art which was not considered in the original prosecu­tion of the application.1 Congress offered ex parte reexamination proceedings as a mechanism that did not require patent owners to offer to surrender their patents and permitted third parties or patent owners to raise substantial new questions (SNQ) of patentability of issued patent claims and have them treated in an administrative proceeding run by the USPTO that did not result in an advisory opin­ion, but in a “Reexamination Certificate” that could cancel patent claims. A SNQ of patentability is defined as a reasonable examiner would consider the prior art important in deciding whether or not the claim is patentable.2

Ex parte reexamination can be requested by the patent owner, the Director of the USPTO, or other (third) parties. When someone other than the patent owner request that the patent be reexamined, that person is referred to as a third-party requester. Note that once reexamination proceedings begin, only the patent owner and the examiner are involved. As such, a third party should only request ex parte reexamination when he has prior art that is on point and will surely invalidate the claims.

Ex parte reexamination proceedings were expected to provide three intended benefits. First a reexamination proceeding was expected to settle validity disputes more quickly and less expensively than the protracted litigation usually involved in such cases. Second, a reexamination proceeding was expected to allow courts to refer patent validity questions to the expertise of the Patent Office. Third, a reexamination proceeding was expected to reinforce investor confidence in the certainty of patent rights by affording the USPTO a broader opportunity to review doubtful patents.3

These benefits of ex parte reexamination proceedings have not, by many accounts, been achieved. For instance, a third-party cannot participate in a meaningful way in the “ex parte” reexamination procedure.4 Consequently, Congress has acted to expand the abilities of third parties to participate by creating an inter partes reexamination procedure.5

Ex parte reexamination benefits for third party requesters include:

1. Anybody can file an ex parte request for reexamination.

2. There are no special jurisdic­tional or standing requirements to be a third party requester.

3. A third party requester can remain anonymous.

4. Ex parte Reexamination is far less expensive than inter partes Reexamination, Patent Interference proceedings or litigation.

5. Once Reexamination is ordered, it continues until a reexamination Certificate is issued, and cannot be withdrawn (not necessarily an advantage to patent owner as requester).

6. The patent owner has a continuing duty of disclosure under 37 C.F.R. §1.56.

7. Once Reexamination is ordered, the patent under reexamination no longer enjoys a presumption of validity governed by 35 U.S.C. § 282.6

8. During Reexamination, claims are given their broadest reasonable interpretation.7 Patent Owner amendment and/or arguments can create prosecution history estoppel.

9. A Request for reexamination can be filed beyond the term of the patent – up to the six additional years of enforceability of the patent with respect to an infringement based on 35 U.S.C. 286 after the patent has expired.

10. A reissue application cannot be filed after the term of the patent has expired.

11. Previously cited art in the patent can be relied upon in a request for reexamination to establish a substantial new question of patentability needed to order reexamination.

12. Additional Requests for reexamination can be filed on additional substantial new ques­tions of patentability of the patent claims and merged with a reexamination proceeding (or already merged other reexamination proceedings) with respect to the same patent. This gives a third party requester further participation in the reexamination proceeding prosecution process.

13. Claims amendments during the proceeding may provide intervening rights to an in­fringer.

14. Admissions against interest, if they are clear, unmistakable and unequivocal, can be used against the patent owner.

Ex parte reexamination drawbacks for a third party Requester include:

1. A third party requester cannot participate in the proceeding beyond filing the initial request for reexamination and commenting on the patent owner’s response to a reex­amination order, should the patent owner file such a response.

2. A third party requester cannot appeal a decision that patent claims are patentable prior to issuance of a reexamination certificate to that effect.

3. A third party requester cannot prevent the issuance of a reexamination certificate deter­mining certain claims patentable.

4. A third party requester cannot prevent a patent owner from amending existing claims and/or adding claims of the same scope or narrower scope to make them stronger and still be infringed by the third party requester.

5. A third party requester cannot prevent a broadened reissue from being filed by the patent owner and having the ex parte reexamination proceeding from being merged with the broadened reissue application, resulting in a merged proceeding that results in broader claims than existed before the request for reexamination was filed.

6. The third party requester cannot prevent ex parte interviews by the Examiner and the patent owner, nor participate in such interviews.

7. A reexamination certificate may issue, making it have gone through USPTO scrutiny twice and considered that much more valid.


  1. 35 United Stated Codes (“U.S.C.”) §§ 302-306.
  2. Manual of Patent Examining Procedure (“M.P.E.P.”) § 2642.
  3. Patlex Corp. v. Mossinghof, 225 U.S.P.Q. 243, 248 (Fed. Cir. 1985).
  4. 35 U.S.C. §§ 301-307.
  5. 35 U.S.C. §§ 301, 311-317.
  6. In re Etter, 225 U.S.P.Q. 1, 3-4 (Fed. Cir. 1985) (stating that “[A] statute setting rules of procedure and assigning burdens to litigants in a court trial does not automatically become applicable to proceedings before the PTO” and “reex­amination is thus neutral, the patentee and the public having an equal interest in the issuance and maintenance of valid patents”).
  7. Etter, 225 U.S.P.Q. at 4.