Claim 22 as written was dependent from claim 38. The district court held claim 22 invalid for "indefiniteness" because there is no claim 38 in the issued patent:

22. A method in accordance with claim 38, wherein said index system is at least: one indexed [sic] of classes of goods and one index of classes of industrial establishments . . . .

This error in dependency of claim 22 is apparent on the face of the printed patent, and the correct antecedent claim is apparent from the prosecution history. The patent application as filed and as prosecuted contained independent claim 38 and dependent claim 39. During prosecution both claim 38 and claim 39 were allowed, but some earlier claims were cancelled. In preparation for printing, the examiner renumbered claim 38 as claim 21, and renumbered claim 39 as claim 22. However, the examiner did not make the corresponding change in the text of claim 22. Thus although claim 39 was renumbered as claim 22, the internal reference to claim 38 was not changed.

The district court found that the PTO was responsible for the error. Mr. Hoffer obtained a certificate of correction in accordance with 35 U.S.C. §254 after this action was filed, changing the antecedent claim "38" to "21." The district court declined to accept the correction, deeming it tardily made. The district court stated that it was powerless to correct the error.

We do not agree that such correction exceeds the judicial power. Absent evidence of culpability or intent to deceive by delaying formal correction, a patent should not be invalidated based on an obvious administrative error. The defendants did not state that they were prejudiced, or even confused, by the error. The district court held that it has no authority to correct or ignore even a typographical error in a patent. That is inaccurate. When a harmless error in a patent is not subject to reasonable debate, it can be corrected by the court, as for other legal documents. See Novo Indus., L.P. v. Micro Molds Corp., 350 F.3d 1348, 1356-57 (Fed. Cir. 2003). Here the error was apparent from the face of the patent, and that view is not contradicted by the prosecution history.