Under the Patent Law of the United States, the Re-examination Statute and its corresponding rules enable any party or person to initiate a re-examination for verifying that the subject-matter or invention in question is patentable. A request for re-examination can be filed by both third parties and the inventor himself during the period of enforceability of the patent.

This mechanism is one step towards the simplification of the process of re-examination and review of patents, in light of a discovery previously overseen information, constituting the body of prior art, which in-turn creates a Substantial and New Question of Patentability (“SNQ”). The ex-parte method of review, unlike Inter Partes Review (“IPR”), involves only the owner of the patent rights and the United States Patent and Trademark Office (USPTO), with the role of the third-party applicant for review being restricted to merely filing the request for review. Further involvement, beyond filing of the review application, of the third-party requester, does not occur unless the patent owner triggers the process of responding to the questions raised by the third-party applicant.

The body of reviewers in the event of an ex-parte re-examination comprises of a panel of three expert and seasoned examiners belonging to the distinctly specialised unit—the Central Re-examination Unit—of the USPTO. The burden of proof vis-à-vis the establishment of a Substantial and New Question of Patentability being created due to the existence of prior art rests with the third-party requester. Given the susceptibility of the review method being converted into a tool for harassment of patent owners, this tilt in the balance scales of the burden of proof acts as a check against such exploitation.

On the question of the exact nature and degree of relevance of “prior act” which is sufficient to raise a Substantial and New Question of Patentability (SNQ). The standard for a valid SNQ to warrant the initiation of an ex-parte review lies in its origin in a specific kind of prior art. The nature of prior art is required to be in the form of a prior patent or a printed publication. Merely pointing to the discovery of an old art or distant references which were previously left unconsidered is not enough to raise a valid SNQ. In case the third-party requester does rely upon old art, in order to convince reviewer of applications of the merit of the SNQ arising from it, the requester is obligated to present the old art through a formerly unconceived window of perspective or in a brand-new light.

Although no legal-estoppel is created upon the conclusion of the ex-parte re-examination proceedings on either of the parties, once a re-examination request is disposed off by the USPTO, no further proceedings or appeals can be initiated by the third-party requester.

Ideally, the USPTO seeks to complete an ex-parte proceeding withing two years of its initiation. Upon the filing of the request by the third-party, or in some instances, the patent owner/inventor themselves, the Central Re-examination Unit has three months to consider the request and decide upon its acceptance or denial. In case of the latter, the requester has an additional period of a month in which he may petition for reconsidering the rejection. In case of grant of request, the patent owner is given two months to file a statement for responding to the assertions made by the requester. The inventor or patent owner is also given an opportunity to ament their claim when confronted with questions. Another tight window of just a month is given to the Central Re-examination Unit to issue First Action, after which the patent owner responds and on the merits of that response the CRU has a set deadline of issuing the Final Office Action within two years since the date of the first filing of the request by the third party.