What is a certificate of correction?
A certificate of correction is an official USPTO document that becomes part of a patent's file and corrects specific types of errors in the issued patent. There are two types: (1) Corrections for USPTO mistakes under 35 U.S.C. § 254 — the Office makes an error in printing or typesetting the issued patent; filed at no charge; the most common example is when the printed patent text differs from what was allowed. (2) Corrections for applicant mistakes under 35 U.S.C. § 255 — mistakes of a typographical or minor character introduced by the applicant in drafting the patent application. Both types of corrections become effective as of the original issue date of the patent.
What errors are correctable
Correctable errors are those that: (1) are clearly evident from the original prosecution record — the USPTO must be able to confirm the error from the application as filed, the prosecution history, or the issued patent itself; (2) do not enlarge the scope of the claims — this is the most important limit; a certificate of correction cannot be used to broaden claims even slightly; (3) do not add new matter — the correction cannot introduce information that was not in the original application; (4) are minor in character (for applicant-error corrections) — not substantive changes to the disclosure or claims. Typical correctable errors: spelling errors, punctuation errors, incorrect cross-reference numbers, missing 'not' in a claim, wrong figure numbers in the brief description of drawings, and typographical errors in chemical formulas or mathematical expressions where the correct version is clear from context.
Filing procedure
To request a certificate of correction, file using USPTO Form PTO/SB/44 (available on the USPTO website). The form requires the patent number, issue date, identification of each error (column, line number, and the erroneous text), and the proposed correction. For USPTO-error corrections under § 254, no fee is required. For applicant-error corrections under § 255, a fee applies (approximately $160 for large entities — check the current USPTO fee schedule). File online through the USPTO's Patent Center system. The request is examined by the USPTO's Office of Patent Publication. If approved, the certificate of correction is printed and mailed to the patent owner and is also published in the Official Gazette and appended to the patent on USPTO Public PAIR/Patent Center.
Limits: what cannot be corrected
Several types of errors cannot be corrected via a certificate of correction and require a reissue application instead: (1) Any change that would enlarge claim scope — even adding a word that makes a claim broader than its original reading. (2) Any new matter — information or elements not present in the original application as filed. (3) Changes requiring substantive re-examination — modifications to claim language beyond typographical corrections. (4) Incorrect inventorship — adding or removing inventors after issuance must be done via a § 256 petition (a separate process from certificates of correction). (5) Changes to the drawings that modify the disclosure. The test: if the 'corrected' version could not have been objectively determined from the original prosecution record by a person of ordinary skill in the art, it is not correctable by certificate of correction.
Certificate of correction vs. reissue
A certificate of correction and a reissue application serve different purposes. A certificate of correction fixes minor clerical or typographical errors while leaving the patent's substance unchanged. A reissue application (35 U.S.C. § 251) is used when the patent contains substantive errors — claims that are too narrow (missing important embodiments of the invention), claims that are too broad (and need to be narrowed to avoid prior art that was missed), or defects in the specification that make it inadequate. Reissue exposes the patent to full re-examination by the USPTO and can take years. Broadening reissue has a strict 2-year deadline from the original patent issue date. Narrowing reissue can be filed at any time during the patent term.
Effect on litigation: the Novo Industries rule
A certificate of correction is effective from the original issue date of the patent — but only against infringers who had notice of the correction. The Federal Circuit in Novo Industries v. Micro Molds Corp. (2003) held that a corrected claim cannot be enforced against conduct that occurred before the correction if the uncorrected claim was clearly invalid or non-infringed. This creates a practical problem: if you discovered during litigation that a claim contained an error that made it unenforceable, and you then obtained a certificate of correction, you may not be able to enforce the corrected claim against the defendant for the pre-correction period. This underscores the importance of carefully reviewing issued patents promptly upon receipt and correcting any errors before litigation arises.
Correcting inventorship separately
Correcting inventorship on an issued patent is NOT done through a certificate of correction. Instead, § 256 provides a separate mechanism: a petition to correct inventorship can be filed by the patent owner (or any named inventor or person who should be named) with supporting evidence explaining the error and why it occurred without deceptive intent. The petition must include a statement from each person to be added or deleted, and a fee. Inventorship correction relates back to the original filing date, which can be important for priority disputes. Adding an inventor who was omitted without deceptive intent corrects the patent; deliberately misjoining inventors with deceptive intent can render the patent unenforceable under the doctrine of inequitable conduct.
Frequently Asked Questions
What can a certificate of correction fix?
A certificate of correction can fix two types of errors: (1) USPTO mistakes under § 254 — errors made by the Office in printing or typesetting the patent, such as errors in the printed patent text that differ from the allowed application. These are corrected at no charge. (2) Applicant mistakes under § 255 — errors in the patent arising from mistakes of a typographical or minor character. These must have been present in the original application as filed, must not involve any change that would require re-examination or constitute new matter, and must be of a minor character. The correction cannot enlarge the scope of the claims — a certificate of correction cannot broaden claims (that requires a reissue application). Both types of corrections require that the error is clearly evident from the record.
How do you file a certificate of correction?
A certificate of correction is filed using USPTO Form PTO/SB/44 or an equivalent request. The request must identify: the patent number, the column and line number of the error, the erroneous text, and the corrected text. For USPTO-error corrections (§ 254), there is no filing fee. For applicant-error corrections (§ 255), the current fee is approximately $160 for large entities (check USPTO fee schedule for current amounts). The USPTO examines the request to confirm the error is evident from the record and that the correction doesn't enlarge claim scope or add new matter. If approved, the USPTO publishes a certificate of correction that becomes part of the official patent record. The correction applies retroactively to the patent's issue date.
What errors cannot be fixed by a certificate of correction?
Errors that cannot be corrected by a certificate of correction include: (1) any correction that would change the scope of the claims — even a minor word change that inadvertently broadens or narrows what is covered requires reissue under § 251; (2) errors that constitute new matter — information that was not in the original application as filed cannot be introduced via a certificate of correction; (3) errors that require re-examination of the application — substantive changes to the specification or claims beyond typographical corrections must go through reissue; (4) errors that are not clearly evident from the original record — the USPTO needs to be able to verify the error from the prosecution history; (5) incorrect inventorship (adding or removing inventors after issuance) — these require a separate petition under § 256 with the appropriate evidence and fee.
When should you use reissue instead of a certificate of correction?
Reissue (35 U.S.C. § 251) is the appropriate mechanism when: (1) claims need to be broadened (only available within 2 years of original grant); (2) claims need to be narrowed (available at any time); (3) the specification needs substantive corrections beyond minor typographical errors; (4) the drawing needs to be corrected in a way that changes what the patent discloses; (5) there was a defect in the patent that makes it wholly or partly inoperative — for example, the claims were drafted too narrowly and don't cover the intended invention. Reissue subjects the patent to re-examination, can take years, and exposes the patent to potential invalidity challenges. The recapture doctrine bars a reissue applicant from reclaiming subject matter surrendered during original prosecution.
Does a certificate of correction retroactively affect pending infringement suits?
A certificate of correction is effective from the date the patent issued — it does not affect rights of persons who relied on the uncorrected patent between the issue date and the correction date. Under Novo Industries v. Micro Molds Corp. (Fed. Cir. 2003), a corrected claim cannot be asserted against infringement that began before the correction was issued if the uncorrected claim was not infringed. This is particularly important in litigation: if the uncorrected patent contained an error that made a claim invalid or non-infringed, a certificate of correction issued after litigation commenced may not be effective against the accused infringer for pre-correction conduct. Correct errors promptly upon discovery to minimize this exposure.