Addressing the relationship between claim construction and a patent’s specification, the U.S. Court of Appeals for the Federal Circuit held that the district court erred by improperly adding a limitation not contained in the specification’s explicit definition of a claim term. Hyperphrase Technologies, LLC v. Google, Inc., Case Nos. 07-1125, -1176 (Fed. Cir., Dec. 26, 2007) (Michel C.J.).

Hyperphrase filed suit against Google, alleging that Google’s AutoLink and AdSense products infringed three of its patents. Google moved for summary judgment of non-infringement, which the district court granted. All but three of the asserted claims contained a limitation requiring a “reference” or “data reference,” which the parties agreed had the same meaning in each of the patents-in-suit. The district court held that the patentee defined “data reference” in the specification of one of the patents as “[a] unique phrase or word which may be used in a record to refer to another record or record segment.” The district court further held that a reference can refer to one and only one record. The district court then held that AutoLink does not infringe the asserted claims because it may link to any of multiple data records and not one and only one record.

The Federal Circuit agreed that the patentee had defined the term “data reference” in the specification, but it held that the district court erred in going beyond that explicit definition to add the “one and only” limitation. The Court noted that although the claim language recites “a” second record instead of “one or more” records, the use of the singular form “a” in conjunction with “comprising” and without narrowing language typically encompasses both singular and plural embodiments.

Furthermore, while the district court observed that “[e]very example in the preferred embodiments involves the use of data references … to identify a single medical record,” the Federal Circuit disagreed and described an embodiment showing the use of a data reference referring to multiple records. Since a claim construction that excludes an embodiment of the relevant claim(s) is typically incorrect, the Federal Circuit rejected the district court’s construction.

Having construed the claims, the Court turned to the judgment of non-infringement. The Court found that the district court’s error in claim construction was not harmless, but that there was insufficient evidence in the record to clarify whether the other limitations of two of the patents were met by AutoLink. The Court affirmed all findings of non-infringement.