Canatex Completion Solutions, Inc. v. Wellmatics, LLC, 159 F.4th 39 (Fed. Cir. Nov. 12, 2025), provides a good explanation and application of the demanding standard for judicial correction via claim construction and shows how an alleged error repeated in the claims and specification can warrant judicial correction. 

Here, the district court determined that a disputed phrase in all asserted claims needed but lacked antecedent basis, which rendered the claims indefinite. 159 F.4th at 41-44.  The claims first introduce “a first part comprising an external connection profile” and later introduce “the connection profile of the second part.” Id.  There is no mention of any connection profile of the second part prior to this later recitation. Id.  Canatex argued for “the connection profile of the second part” to be construed as “the connection profile of the first part.” Id.  It agreed the limitation as recited lacked antecedent basis but said the language “second part” was a clear clerical error that the district court could correct. Id.  This asserted error also appeared once in the Abstract and twice in the written description. Id.

The district court disagreed and concluded the error alleged was not apparent from the face of the patent and the correction not as simple as Canatex claimed. Id.  It reasoned that the “pervasiveness of the error” in both the claims and the specification suggested “an intentional drafting choice.” Id.  The district court also suggested the drafter may have intended to recite “a connection profile of the second part,” and erroneously used “the” instead of “a”. Id.  The district court further said the failure to seek correction from the PTO pursuant to 35 U.S.C. § 255 suggested the error was neither minor nor evident on the face of the patent. Id.  It concluded the limitation at issue lacked antecedent basis and the asserted claims were invalid for indefiniteness. Id.  The parties stipulated to entry of final judgment. Id. at 45.  Shortly after final judgment was entered and Canatex appealed, Canatex sought correction of the disputed language from the PTO pursuant to § 255 and 37 C.F.R. § 1.323 and made arguments similar to those made on appeal. Id. at 45 n.1.  The PTO denied Canatex's proposed correction in March 2025 and, without elaboration, stated that the “corrections requested [sought] to change the scope of the patented claims.” Id.

Addressing Canatex’s challenge to the district court’s decision, the Court observed it has previously made corrections for “an obvious and correctable error in the claim, the construction of which is not subject to reasonable debate.” Id. at 45-46.  Discussing the “very demanding” standards for judicial correction of a claim term, the Court said its cases articulate several elements of the standard. Id.  One necessary requirement “is that the error must be evident from the face of the patent, i.e., obvious, as determined from the point of view of one skilled in the art.” Id. (internal quotation marks and citations omitted).  Another necessary requirement “is that correction is appropriate only if (1) the correction is not subject to reasonable debate based on consideration of the claim language and the specification and (2) the prosecution history does not suggest a different interpretation of the claims.” Id. (same).  The Court noted it has also ruled that “a district court may correct obvious minor typographical and clerical errors in patents” and said that while it has not stated this element as a necessary requirement, which it may well be, in the present case it assumed it was. Id.  

The Court explained that the foregoing standard, rigorously applied as required, “takes account of the primacy of ‘the public notice function of patents.’” Id. at 46.  Thus, if an error is evident on the face of the patent, and the correction advanced the only reasonable understanding of the intrinsic evidence, “at least if the correction makes only a small change in claim language, [then] the relevant reader of the patent—a person of ordinary skill in the art—is constructively aware of the intended meaning, to be given effect by a court carrying out claim construction with its established, limited role for correction.” Id. (cleaned up).  The Court further explained that the standard respects Congress's choice to make only prospective the corrections the PTO makes under § 255. Id. (noting the statute “covers a broader class of errors—which, for example, are not limited to obvious errors and so can result in a claim scope different from the one that relevant readers would understand from the pre-alteration language”).   A judicial correction thus “determines the meaning the claim always had and the rigorous standard for such a correction avoids the alteration-of-understanding problem underlying the prospectivity rule for PTO correction.” Id.  The Court lastly said the standard “is akin to a standard for judicial correction of other legal language set forth in the prominent guide to legal interpretation generally, ANTONIN SCALIA & BRYAN A. GARNER, READING LAW: THE INTERPRETATION OF LEGAL TEXTS, p. 234 (2012): ‘A provision may be either disregarded or judicially corrected as an error (when the correction is textually simple) if failing to do so would result in a disposition that no reasonable person could approve.’” Id.

For reasons that overlap, the Court determined the existence of an error in the phrase at issue was obvious on the face of the patent and there was only one reasonable correction, considering all the intrinsic evidence, including the prosecution history. Id. at 46-47.  That correction—changing “second” to “first”—plainly was “simple and ‘minor’ as a textual matter.” Id.  It followed that the fact of error and uniqueness of the small correction meant the error was “properly characterized as a minor clerical or typographical error.” Id.

The Court went on to elaborate on (1) the obviousness of the error on the face of the patent and (2) the uniqueness of a reasonable correction. Id.  It explained how the claim language itself showed the error was evident on the face of the claim, as well as on the face of the specification. Id. at 47.  The Court also determined the proper correction was “not subject to reasonable debate based on consideration of the claim language and the specification.” Id. at 47-48.  The only reasonable correction to the Court was to change “second” to “first.” Id.  It reasoned the claim language as a whole and the specification both show this is what “the very character of the invention requires.” Id. at 48.  Defendants’ argument that there are other reasonable corrections and list of potential corrections were rejected. Id. at 48-49.  Further, the Court saw no basis for concluding the patent’s prosecution history suggested a construction of the disputed language other than what Canatex proposed. Id. at 49.  In particular, there was no finding below nor any persuasive argument on appeal that the prosecution history precluded correction if, as the Court concluded, the error was evident on the face of the patent and the proposed correction the only reasonable one based on the claims and specification. Id.

The Court reversed the judgment and remanded for further proceedings under the corrected claim construction.