What is supplemental examination at the USPTO?

Supplemental examination is a post-grant USPTO procedure that lets a patent owner ask the Office to consider, reconsider, or correct information believed to be relevant to the patent. It is authorized by 35 U.S.C. § 257, added to the patent statute by the Leahy-Smith America Invents Act. The procedure became available on September 16, 2012.

The primary strategic value is a powerful statutory defense: a successful supplemental examination can insulate a patent from an inequitable conduct attack based on information the examiner never saw, saw incorrectly, or evaluated in error during original prosecution.

Who can file

Only the patent owner may request supplemental examination; third parties have no right to initiate the proceeding. More than one supplemental examination request for the same patent may be filed at any time during the period of enforceability of the patent.

What information can be submitted

The scope of submittable information is substantially broader than in a standard ex parte reexamination. A supplemental examination request is not limited to patents and printed publications; it may include any information believed to be relevant to the patent, such as sales invoices or transcripts of audio or video recordings.

A request may raise patentability issues under multiple statutory provisions, including subject matter eligibility under 35 U.S.C. § 101 and written description, enablement, and definiteness under 35 U.S.C. § 112, as well as anticipation, obviousness, and double-patenting. This breadth allows an owner to address patentability concerns that standard ex parte reexamination cannot reach.

How supplemental examination works: a two-step process

Step 1: the supplemental examination

After receiving a proper request, the USPTO issues a certificate stating whether the submitted information raises a substantial new question of patentability. During this proceeding, interviews are not permitted and no amendments may be submitted. The proceeding is an administrative review, not a prosecution track.

Step 2: conditional ex parte reexamination

If the certificate indicates that a substantial new question of patentability is raised, the USPTO orders ex parte reexamination of the patent. That reexamination is not limited to patents and printed publications, unlike a standard ex parte reexamination request filed under 35 U.S.C. § 302.

One procedural tradeoff: in reexamination triggered by supplemental examination, the patent owner does not have the right to file a statement under 35 U.S.C. § 304.

If the certificate finds no substantial new question of patentability, no reexamination is ordered, and the patent receives the benefit of the inequitable conduct shield for the submitted information.

The inequitable conduct shield

This is the central reason most patent owners use supplemental examination. Under 35 U.S.C. § 257(c), a patent shall not be held unenforceable on the basis of conduct relating to information that had not been considered, was inadequately considered, or was incorrect in a prior examination of the patent, if that information was considered, reconsidered, or corrected during a supplemental examination of the patent.

In practical terms: if an owner discovers information that may not have been properly disclosed during prosecution, or that was presented incorrectly, supplemental examination offers a path to address that exposure before litigation arises. The shield applies whether or not reexamination is ultimately ordered.

Exceptions: when the shield does not apply

The shield has two explicit statutory carve-outs:

Civil action bar. The shield does not apply to an allegation of unenforceability pled with particularity in a civil action filed before the date of the supplemental examination request. A patent owner who is already a defendant in an infringement suit cannot neutralize an already-filed inequitable conduct defense by filing a supplemental examination request after the suit is underway.

FDA/ANDA bar. The shield does not apply to a notice filed under the Federal Food, Drug, and Cosmetic Act before the date of the supplemental examination request.

Material fraud is not protected

The inequitable conduct shield does not extend to material fraud. If the USPTO determines that material fraud on the Office may have been committed, it refers the matter to the Attorney General; this referral authority is separate from the inequitable conduct shield and is not displaced by it.

Supplemental examination vs. ex parte reexamination

Any person may, at any time during the period of enforceability of a patent, file a request for ex parte reexamination. That request must be based on prior art patents or printed publications. Supplemental examination differs from ex parte reexamination in several ways:

Practical considerations

File before litigation. The civil action bar means the shield is unavailable for inequitable conduct allegations already pled with particularity before the supplemental examination request is filed. Proactively auditing a patent portfolio for disclosure gaps and acting before litigation is the only way to preserve the shield.

Not limited to prior art. Because supplemental examination can address § 101, § 112, and other non-prior-art issues, it reaches a broader range of prosecution deficiencies than ex parte reexamination.

Weigh the reexamination risk. If the submitted information is genuinely material, the USPTO will likely find a substantial new question of patentability and order reexamination. An owner should assess whether the patent's claims are likely to survive that reexamination before using supplemental examination as a shield strategy.

No third-party participation. Because only the patent owner initiates the proceeding, competitors have no mechanism to participate in or oppose a supplemental examination request.