The U.S. Court of Appeals for the Federal Circuit reversed a lower court’s summary judgment ruling that a patent claim was indefinite based on an obvious claim drafting error. CBT Flint Partners, LLC v. Return Path, Inc., Case Nos. 10-1202, -1203 (Fed. Cir., Aug. 10, 2011) (Lourie, J.).

The plaintiff alleged infringement of two patents relating to systems for charging a fee for sending spam to e-mail recipients. In the preferred embodiment, the invention is implemented as part of an internet service provider, in which the ISP checks incoming spam to determine if the proper fees have been paid.

A single patent claim was at-issue on appeal. That claim read, in relevant part, “a computer in communication with a network, the computer being programmed to detect analyze the electronic mail communication sent by the sending party.”

A day after issuing a claim construction ruling, the lower court granted summary judgment of invalidity of the contested patent claim, concluding that the claim was not amendable to construction and was, thus, indefinite under 35 U.S.C. §112, ¶ 2. The district court agreed with both parties that the claim contained a drafting error, referring to the “detect analyze” phrase, but concluded that because there were three possible ways to correct the error, the appropriate correction was subject to reasonable debate. The court concluded that it was not authorized to correct the drafting error.

The Federal Circuit, reviewing the grant of summary judgment de novo, disagreed. The Court held that the contested claim included an obvious and correctable error, the construction of which was not subject to reasonable debate and, thus, the district court was authorized to correct the error. In a patent infringement suit, stated the Federal Circuit, a court may correct an obvious error in a claim if the correction is not subject to reasonable debate based on the claim language and specification and the prosecution history does not suggest a different interpretation of the claim. This authority survived the enactment of 35 U.S.C. §§ 254 and 255. The Court stated that corrections are not appropriate if they are substantively significant and require guesswork. Further, a district court must consider any proposed correction from the point of view of one skilled in the art.

The Federal Circuit parsed the “detect analyze” phrase in light of the three possible meanings considered by the district court and then construed the contested language. The Court found that under all three possible meanings, the scope of the contested claim would require that an e-mail be both detected and analyzed. Thus, a person skilled in the art would understand that all three possible corrections would result in the same claim scope. The Court found the proposed correction of the claim was not subject to reasonable debate and nothing suggested a contrary interpretation.