Correcting Patent Claim Errors: Federal Circuit Guidance on the Limited but Important Role of Courts.

By: Nayyer Siddiqi

Should courts use claim construction to fix flaws in patent claims, and if so, what limits and guidelines should apply? The Federal Circuit explored these issues recently in the matter of Canatex Completion Solutions, Inc. v. Wellmatics, LLC, No. 2024-1466 (Fed. Cir. Nov. 12, 2025). In this case, the Federal Circuit held that when an error in a claim is evident or obvious on the face of the patent and only one reasonable correction exists, courts possess the authority to correct the claim error through claim construction. This ruling emphasizes the strict boundaries around judicial correction of claims in issued patents.

Background

The patent at issue, U.S. Patent No. 10,794,122, issued in 2020 and claims a releasable connection device used mostly for oil and gas wells. During downhole operations, operators may deploy tools and components into wellbores using tool strings such as wireline or tubing strings. A releasable connection device is useful when circumstances require leaving a component downhole, or when a component becomes lodged in the wellbore. The patented releasable connection device features two interlocking parts that remain secured during normal operations but may be separated on demand. The three independent claims each include language stating that a locking piston moves “to release the connection profile of the second part.” This phrase presented an antecedent basis problem because the earlier portion of each claim identified “a connection profile of the first part” rather than the second part.

Moving forward to September 2022, Canatex sued Wellmatics in the U.S. District Court for the Southern District of Texas, alleging infringement of their ’122 patent. In turn, Wellmatics challenged the validity of the ’122 patent, arguing that the asserted claims were indefinite for lack of an antecedent basis for the phrase at issue, “the connection profile of the second part.” The Southern District of Texas found the claims to be invalid as indefinite, rejecting Canatex’s argument that “second” was an obvious error that should be construed as “first.” Canatex appealed to the Federal Circuit. During the pendency of the appeal, Canatex sought a certificate of correction from the U.S. Patent and Trademark Office to change “second” to “first.” However, the U.S. Patent and Trademark Office rejected the petition, finding that the requested correction was more than a clerical or typographical mistake.

The Federal Circuit’s Analysis

The Federal Circuit reversed the decision of the Southern District of Texas, concluding that the claims in question were not indefinite. The matter was reviewed de novo as a matter of claim interpretation based entirely on intrinsic evidence. The analysis of the Federal Circuit was grounded in the Supreme Court’s 1926 decision in I.T.S. Rubber Co. v. Essex Rubber Co., which established that courts possess authority to correct obvious clerical errors in patent claims through claim construction. That case involved a patent covering rubber heel lifts for shoes in which one claim inadvertently omitted the word “rear” before “upper edge.” The Supreme Court held that the omission resulted from clerical error, and that both the applicant’s attorney and the patent examiner understood that the word “rear” was included in the claim. The I.T.S. Rubber decision established that judicial correction is appropriate only when the error is evident and the intended meaning was understood by the examiner during the prosecution phase.

Building on I.T.S. Rubber and other cases, the Federal Circuit in Canatex identified three requirements for when judicial correction is permissible. First, the error must be evident from the face of the patent from the perspective of a skilled artisan. Second, the correction cannot be subject to reasonable debate based upon review of the patent document and prosecution history. Third, the correction must be limited to obvious minor typographical and clerical errors. While all three elements had been derived from the prior precedent, the Federal Circuit noted it had not previously explicitly stated that the third element was necessary and carefully avoided holding that it constitutes a mandatory requirement.

Applying this framework, the Federal Circuit found that the error was correctable judicially. The court noted that a skilled artisan would recognize that the phrase “the connection profile of the second part” lacks antecedent basis because the claims did not previously mention any connection profile of the second part. More particularly, the term releasing “the connection profile of the second part” made no functional sense, as a person of ordinary skill in the art would recognize that what gets released through radial expansion must be the same component that was already there, i.e., the connection profile of the first part. Additionally, the figures in the patent showed no connection profile in the second part. The Federal Circuit concluded that a “relevant reader” would have understood the errors when viewing the entire document.

A distinguishing case noted by the Federal Circuit was Chef America, Inc. v. Lamb-Weston, Inc., 358 F.3d 1371 (Fed. Cir. 2004), where the court declined to correct what the patentee had argued was an obvious error. The Chef America patent claimed a process requiring “heating the dough to a temperature in the range of about 400°F to 850°F,” which would burn the dough to a crisp. The patentee had argued that the limitation meant heating the oven to that temperature, as opposed to heating the dough (heating “at” rather than heating “to”). The Federal Circuit declined to make the correction, pointing out multiple aspects of the prosecution history that suggested a different interpretation. The court found no relevant prosecution history in Canatex to deny the proposed correction, distinguishing Chef America on the basis of prosecution history.

Takeaways

Canatex reinforces the limited but important role that courts may play in correcting patent claim errors through claim construction. Through application of a rigorous test, the court avoids venturing into substantive claim redrafting while providing patentees a way to preserve claim validity in a situation where the intrinsic evidence is clear regarding both the error and the sole reasonable correction.

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Background

The Federal Circuit’s Analysis

Takeaways

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