Federal Circuit Clarifies Claim Construction Rules

In Phillips v. AWH Corp., 415 F.3d 1303, 75 USPQ2d 1321 (Fed. Cir. 2005) (en banc), the Federal Circuit conducted a rehearing en banc in order to review a panel decision in which appellate panel construed term “baffle,” in claims directed to impact-resistant building modules, as limited to modules providing impact or projectile resistance oriented at angles other than 90 degrees based upon the intrinsic record and without using the broader ordinary meaning of the term.  The main question to be answered was whether “the public notice function of patent claims [is] better served by referencing primarily to technical and general purpose dictionaries and similar sources to interpret a claim term or by looking primarily to the patentee’s use of the term in the specification?”  In its decision, the Federal Circuit held, en banc, that the intrinsic record of the specification and prosecution history should be used to define the claim scope, with the use of dictionaries being reserved to clarify meanings not made clear in the intrinsic record in the same way as extrinsic evidence such as expert testimony.

Specifically, the Federal Circuit affirmed that the claims are interpreted in accordance with Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 39 USPQ2d 1573 (Fed. Cir. 1996), which emphasizes the importance of intrinsic evidence (i.e., specification and prosecution history) as the primary or initial claim construction tool.  The Federal Circuit rejected the use of dictionaries and treatises as a primary method of construing claim features as held in Tex. Digital Sys. v. Telegenix, Inc., 308 F.3d 1193, 64 USPQ2d 1812 (Fed. Cir. 2002).  In making this decision, the Federal Circuit clarified that the “ordinary meaning” of a claim term is the meaning to a person skilled in the art at the time of the invention (i.e., as of the effective filing date of the patent application) after reading the claim term not only in the context of the particular claim in which the disputed term appears, but also in the context of the entire patent, including the specification and prosecution history.  While extrinsic evidence, which “consists of all evidence external to the patent and prosecution history, including expert and inventor testimony, dictionaries, treaties and technical references” is “less significant than the intrinsic record,” this extrinsic evidence can still be useful to help educate the district court regarding the field of invention and how a person skilled in the art would understand the “ordinary meaning” of a claim term when read in the context of the specification and prosecution history.

In discounting the use of extrinsic evidence as a primary tool for claim construction, the Federal Circuit held that “extrinsic evidence in general as less reliable than the patent and its prosecution history” for several reasons:

  • extrinsic evidence by definition is not part of the patent and does not have the specification’s virtue of being created at the time of patent prosecution for the purpose of explaining the patent’s scope and meaning
  • extrinsic publication may not be written by or for skilled artisans and therefore may not reflect the understanding of a skilled artisan in the art.
  • extrinsic evidence such as expert reports and testimony is generated at the time of and for the purposes of litigation and thus can suffer from


bias that is not present in intrinsic evidence.

  • there is a virtually unbounded universe of potential extrinsic evidence (e.g., different dictionaries may contain different sets of definitions for the same words) such that each party will naturally choose the pieces of extrinsic evidence most favorable to its cause, leaving the court with the considerable task of filtering the useful extrinsic evidence from the fluff; and
  • undue reliance on extrinsic evidence can undermine the public notice function of patents.

With this claim construction methodology, the Federal Circuit interpreted the claims de novo.  Claim 1, which recites “further means disposed inside the shell for increasing its load bearing capacity comprising internal steel baffles extending inwardly from the steel shell walls”, there are three clear requirements with respect to the “baffles”: 1) the baffles must be made of steel; 2) the baffles must be part of the load-bearing means for the wall section; and 3) the baffles must be pointed inward from the walls.  From the intrinsic evidence, the Federal Circuit held that the District Court’s interpretation of the term “baffles” was improper.

Specifically, the Federal Circuit looked to dependent claims 2 and 17, which further define that the “baffles” are disposed at “angles for deflecting projectiles such as bullets” that penetrate the outer shell, and dependent claim 6, which further provides an additional requirement for the baffles as being interlocked “to form an intermediate barrier”.  Thus, under the doctrine of claim differentiation, claim 1 would have a scope of at least commensurate with these depending claims such that the term “baffles” in claim 1 is not limited to elements which deflect bullets.

The Federal Circuit also noted that the specification further discusses several other purposes served by the baffles beyond deflection of bullets.  For example, the baffles are described as providing structural support for one of the wall, as shown in FIG. 4 and FIG. 6.  In addition, the baffles are also described as providing “for overlapping and interlocking … to produce substantially an intermediate barrier wall between the opposite [wall] faces, and thus, creating small compartments that can be filled with either sound and thermal insulation or rock and gravel to stop projectile, as shown in FIG. 7.  Thus, there was no statement in the specification limiting the term “baffles” to elements which deflect bullets alone.

In view of the multiple objectives to be served by the “baffles” as described in the specification and in view of the doctrine of claim differentiation, the term “baffles” need not be read restrictively to require that “baffles” must be used to deflect bullets and, thus, must have angles at other than 90 degrees angle.

As a result, the Federal Circuit rejected the accused infringer’s arguments (AWH) in favor of a restrictive definition of the term “baffles”, reversed the summary judgment of non-infringement, and remanded the infringement claims back to the district court for further proceedings.


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