Despite the Federal Circuit's 2005 en banc decision in Phillips v. AWH Corp., district courts and the Federal Circuit continue to struggle with how to draw the line between using a patent's specification to properly interpret the claims and improperly importing limitations from the specification into the claims. A pair of recent Federal Circuit claim construction decisions illustrate this ongoing debate. In one case, the majority chose to narrow the scope of the claims using the specification. In the other, the majority appeared to rely on the specification to construe claims more broadly than a strict reading might suggest. But not all members of the panels were in agreement with either decision, as can be seen from the vigorous dissents filed.

Retractable Techs., Inc. v. Becton, Dickinson and Co., 653 F.3d 1296 (Fed. Cir. July 8, 2011)

In Retractable Techs., the patent at issue related to retractable syringes, which are medical syringes that feature a needle that retracts into the syringe body after the syringe is used. Judge Lourie, writing for the majority, reversed the district court's claim construction and found the term “body,” as used in the patent, required a one-piece structure, rather than including multiple-piece structures. The majority opinion explained that “none of the [patent] claims expressly recite a body that contains multiple pieces.” The majority looked at the specification and found that it distinguished “prior art syringes comprised of multiple pieces” while not disclosing a multiple-piece body as part of the claimed invention.

In dissent, Judge Rader opined that the majority had improperly imported limitations from the specification into the claims. Judge Rader reasoned that the ordinary and customary meaning of the term “body” “does not inherently contain a one-piece structural limitation,” and “neither the claim language nor the written description evinces intent by the patentee to limit the scope of ‘body' to one-piece bodies.” Judge Rader also noted that two dependent claims expressly recited a one-piece body limitation, which suggested that the independent claim was not so limited under the doctrine of claim differentiation.

While joining the “thorough and well reasoned opinion” of Judge Lourie, Judge Plager wrote a short concurrence. Judge Plager noted, “[H]owever much desired by the claim drafters, who want claims that serve as business weapons and litigation threats … the claim cannot go beyond the actual invention that entitled the inventor to the patent. For that we look to the written description. … I have written elsewhere about the curse of indefinite and ambiguous claims, divorced from the written description, that we regularly are asked to construe, and the need for more stringent rules to control the curse. … I understand how a perfectly competent trial judge can be persuaded by the siren song of litigation counsel to give the jury wide scope regarding what is claimed. But it is a song to which courts should turn a deaf ear if patents are to serve the purposes for which they exist, including the obligation to make full disclosure of what is actually invented, and to claim that and nothing more.”

Markem-Imaje Corp. v. Zipher Ltd., 100 U.S.P.Q. 2d 1068 (Fed. Cir. 2011)

In Markem-Imaje, by contrast, the Federal Circuit majority arguably ignored potentially limiting statements contained in the patent's specification. The patent at issue related to devices for transfer printing, a process where ink is carried by a ribbon that is moved into contact with the substrate to be printed, and a print head impresses upon the ribbon and causes the ink to transfer from the ribbon to the substrate.

The central issue for claim construction was whether the claims required “some method of deriving a tension measurement.” The defendant argued that the claim itself did not recite measuring tension, and reading such a limitation into the claims would “violate the mandate of Rambus Inc. v. Infineon Tech. AG that ‘the claims need not recite every component necessary to enable operation of a working device.'” The majority agreed and explained that, while deriving a tension measurement may be required to make the claimed device operational, it was not proper for the district court to incorporate such a method into the claim construction. For example, the court stated, “A claim to an engine providing motive power to a car should not be construed to incorporate a limitation for an exhaust pipe, though an engine may not function without one.”

Judge Newman dissented, pointing out that the specification contained statements about measuring tension. In Judge Newman's view, “while the invention is flexible as to how tension is measured, and permits measurement through indirect methods, some method of measurement is contemplated and required, as found by the trial court.” Judge Newman disagreed with the majority's interpretation of Rambus and explained, “This court has no authority to enlarge the scope of the patent beyond what the patentee described as its invention, notwithstanding my colleagues' curious analogy to a car and its tailpipe.”


Though it has been more than six years since the en banc Federal Circuit clarified claim construction law in Phillips v. AWH Corp., with scores of subsequent claim construction decisions by various panels of the court in the intervening time period, the Retractable Techs. and Marken-Imaje decisions show that the Federal Circuit still struggles with the basic issue of how to use the specification in construing claims. These two examples are not alone, as Federal Circuit panels have split over claim construction issues roughly a dozen times since the beginning of 2010. Perhaps it is nearing time for the Federal Circuit to take another claim construction case en banc to further clarify claim construction law and provide additional guidance to both itself and district courts.