In patent claims, the singular definite articles “a” and “an” are construed to mean “one or more” unless the claims, specification, or prosecution history clearly suggest otherwise.

The patentee of technology that enables computers to access one another remotely via the Internet brought suit against an alleged infringer. The district court construed the crucial claim term “location facility” as a multifunctional component contained on a single physical computer. Because the alleged infringer’s technology spread the functionalities of the “location facility” across multiple computers, the district court granted summary judgment of noninfringement.

The Federal Circuit vacated the district court’s decision. Reviewing the construction of “location facility” de novo, the Federal Circuit concluded that the district court improperly interpreted the patent’s use of singular articles and pronouns to mean that the functions of the “locator facility” had to be performed on a single computer. In patent claims, the words “a” and “an” carry the meaning, “one or more,” even if later portions of the patent refer back to the claims using definite articles. This rule of construction applies unless the claims, specification, or prosecution history clearly necessitate a departure; mere ambiguity or inconsistent usage of the singular and plural is insufficient to overcome application of the general rule.

The Federal Circuit also rejected the alleged infringer’s arguments that the patentee had disclaimed a multiple-location “location facility” during an inter partes reexamination of the patent. The expert statements the alleged infringer relied on did not address whether the “location facility” could be distributed across several computers. Additionally, the patentee’s cancellation of one of several claims disclosing multiple locator server computers did not undermine the examiner’s finding that the specification “clearly” contemplated the use of more than one physical computer.

A copy of the opinion can be found here.