A limitation for external cables or wires cannot be read into a claim where this element is only disclosed by a statement in the specification addressing deficiencies in the prior art.

The patents at issue cover methods and devices for monitoring and reporting an analyte in the bloodstream, and using an electromagnetic sensor to provide that information to a patient. The patentee filed a lawsuit in United States District Court for the District of Delaware and the defendants requested an ex parte reexamination before the PTO. After losing before the Board of Patent Appeals and Interferences (the "Board"), and having its requests for rehearing denied, the patentee appealed the Board's decision to reject multiple claims of the patents under ex parte reexamination. The Federal Circuit vacated the rejections and remanded to the Board for additional proceedings.

The common specification of the patents described shortcomings of the prior art devices that used wires and cables to connect components of the machines that restricted patients’ range of motion. In its review of the examiner’s rejection, the Board construed the term, "electrochemical sensor" to include external cables or wires even though this element was only included in a single statement in the specification that discussed the prior art. Under this construction, the Board determined that the claims were invalid. In its unsuccessful requests for rehearing, the patentee argued that the Board improperly relied on a statement in the patents’ specification to read the limitation into the claim.

At issue here was whether or not the broadest possible construction of "electromechanical sensor" included external cables and wires. On appeal, the PTO argued that the patentee was required to make a "clear disavowal" or "express disclaimer" of the claim scope to exclude this limitation from the claim.

Under Federal Circuit precedent, "[a]lthough the PTO emphasizes that it [is] required to give all claims their broadest reasonable construction, . . . this court has instructed that any such construction be consistent with the specification." The Federal Circuit held that here, where the only mention of a sensor with external cables or wires was a single statement addressing deficiencies in the prior art, this limitation could not be read into the claim.

A copy of the opinion can be found here.