Errors In Issued Patent Claims

US court of Appeals for the Federal circuit decides Fargo v. IRIS. This case deals with what happens when a patent claim being litigated has an obvious error in it. Fargo’s patent was for a printer ribbon supply rolls with identifying indicia and sensors to detect the indicia during operation of a printer. Fargo’s patent attorney argued that the clause: “the second supports other than the being oriented at known positions relative to the home position and at least one second support carrying a removable unmagnetized magnetic material identifier indicia” in claim 8 of US patent 5,755,519 could be understood and corrected by the Court.

The law regarding errors in claims is that a district court may only correct an error in a patent by interpretation of the patent “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.” Since, this clause was ambiguous, the Appeals court denied Fargo’s appeal and found the claim to be invalid. Also, all the claims that depended from claim 8 were found to be invalid because of the error in claim 8.