Erroneous wording of a claim may be subject to judicial correction as a matter of claim construction in narrow circumstances. See, e.g., I.T.S. Rubber Co. v. Essex Rubber Co. 272 U.S. 429, 442–43 (1926) (correcting an obvious and minor mistake in a claim, namely that the word “rear” was erroneously omitted through clerical error and the claim had to be construed to include the word where the correction was “not in any real sense [ ] a re-making of the claim” but instead “merely g[ave the claim] the meaning which was intended by the applicant and understood by the examiner”); Pavo Solutions v. Kingston Technology Company, Inc., 35 F.4th 1367, 1373–74 (Fed. Cir. 2022); CBT Flint Partners, LLC v. Return Path, Inc., 654 F.3d 1353, 1358–59 (Fed. Cir. 2011); Ultimax Cement Manufacturing Corp. v. CTS Cement Manufacturing Corp., 587 F.3d 1339, 1346–47 (Fed. Cir. 2009); Group One, Ltd. v. Hallmark Cards, Inc., 407 F.3d 1297, 1303 (Fed. Cir. 2005); Novo Industries, L.P. v. Micro Molds Corp., 350 F.3d 1348, 1357 (Fed. Cir. 2003). 

First, one necessary requirement is that “the error must be ‘evident from the face of the patent,'” Pavo, 35 F.4th at 1373 (quoting Group One, 407 F.3d at 1303), i.e., obvious, as determined “‘from the point of view of one skilled in the art,'” id. (quoting Ultimax, 587 F.3d at 1353). 

Second, another necessary requirement is that “[c]orrection 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.'” Pavo, 35 F.4th at 1373 (quoting Novo, 350 F.3d at 1354). 

Third, “[a] district court may correct ‘obvious minor typographical and clerical errors in patents.'” Id. (quoting Novo, 350 F.3d at 1357).

The standard for judicial correction of patent claims 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 (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. at 234.

In Canatex Completion Solutions, Inc. v. Wellmatics, LLC, No. 2024-1466, __ F.4th __ (Fed. Cir. Nov. 12, 2025), the Federal Circuit reversed a district court's holding of indefiniteness, and instead held that an obvious claim error may be corrected by a court through claim construction where the error is evident on the face of the patent and only one reasonable correction exists. 

In Canatex, U.S. Patent No. 10,794,122 claimed a “releasable connection” tool used in oil and gas wells. The tool comprises a “first part” and a “second part” which lock together during normal operations but can be separated. If the first part becomes stuck due to debris lodged in the wellbore, the two parts of the device can be disconnected from each other, allowing the second part to be retrieved immediately while the first part remains downhole for later retrieval. 

The asserted independent claim stated that a locking piston moves “to release the connection profile of the second part.” But “the connection profile of the second part” had no antecedent basis in the claim because the claim previously recited “a connection profile of the first part.” Thus, the issue was whether it was sufficiently clear that “second” in the underlined phrase must mean (and thus be corrected to) “first.” 

The Federal Circuit concluded that Canatex is entitled to judicial correction in this case. 

For reasons that overlap, the existence of an error in the phrase at issue is evident (obvious) on the face of the patent, and there is only one reasonable correction, considering all the intrinsic evidence, including the prosecution history. That correction, changing “second” to “first,” plainly is simple and “minor” as a textual matter. And it follows that the fact of error and uniqueness of the small correction mean that the error is properly characterized as a minor clerical or typographical error. 

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The phrase at issue plainly requires an antecedent (“the connection profile of the second part”), but no “connection profile of the second part” has previously been mentioned in the claim. . . . A relevant reader would immediately see that something was off in language that speaks of releasing, through the releasable engagement profile's radial expansion, anything but the very component embraced in the connected state (the connection profile of the first part)—as made clear even by the name “releasable engagement profile.” An undefined notion of the second part's engagement component releasing a part of the second part itself is jarringly anomalous in this claim. All of this makes the error evident on the face of the claim.

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     We also conclude that the proper correction is not “subject to reasonable debate based on consideration of the claim language and the specification.” Novo, 350 F.3d at 1354. The only reasonable correction is the changing of “second” to “first” in the claim language at issue. That is what the claim language as a whole and the specification both show “the very character of the invention requires.” Alloc, Inc. v. International Trade Commission, 342 F.3d 1361, 1370 (Fed. Cir. 2003).

The Federal Circuit also distinguished this case from Chef America, Inc. v. Lamb-Weston, Inc., 358 F.3d 1371, 1374 (Fed. Cir. 2004) which had held that a court may not “redraft claims, whether to make them operable or to sustain their validity.” The independent claims at issue on Chef America included the step of “heating the resulting batter-coated dough to a temperature in the range of about 400° F. to 850° F.”; but it was undisputed that the dough would then be “burned to a crisp.” Id. at 1373–74. In Chef America, nothing in the specification or the prosecution history suggested that the patentee meant for the dough to be cooked "at" 400° F rather than "to" 400° F. “To the contrary, the prosecution history suggests that the patentees intentionally used "to" rather than "at" in drafting the temperature requirements of the claim” to overcome a Section 112 enablement rejection. Chef America, 358 F.3d at 1374. Moreover, Chef America did not contend that the use of "to" rather than "at" was a draftsman's mistake, and made no attempt to have such an error corrected by the USPTO or the district court. 

Instead, Canatex was more akin to Pavo where the alleged claim error (i.e., the case pivoting with respect to a component of which it forms a part) resulted in something that did not make sense rather than “a realistic but perhaps undesirable result, i.e., cooking dough to 400° F and burning it.” Pavo, 35 F.4th at 1375.

The Federal Court concluded “it is evident that the claim contains an error and that a relevant artisan would recognize that there is only one correction that is reasonable given the intrinsic evidence.” In particular, “the correction of ‘second' to ‘first' is the unique correction that captures the claim scope a reasonable relevant reader would understand was meant based on the claim language and specification.”