The ’663 patent is entitled “Coaxial Cable Test Instruments,” and was issued to Joseph V. Kapusta. The invention relates to a continuity testing instrument for coaxial cables that provides a signal to indicate the malfunction of any installed coaxial cable component of a television network. The tester instrument consists of circuitry that is contained in a hand-grip size case. The circuit within the hand-grip size case is connected to a coaxial cable through a connector so that an operator can quickly and reliably check a cable component malfunction.

Here are the convolutions of the district court.

The district court construed the only disputed claim term, “hand-grip size case,” to require lower size limits that are “no smaller than the width of an adult palm, so that it can be grasped firmly in one’s hand; no smaller than 1 inch in width; and of a rectangular shape.” Claim Construction Order, at 6. In construing “hand-grip size case,” the court found the term to be ambiguous because of its uncertain size and shape. The court observed that the specification and the prosecution history do not define the term. Id., at 5. The only place in the patent that articulates the meaning of the term “hand-grip size case,” according to the court, is “the one preferred embodiment described in the specifications and shown in the drawings, namely a one inch by two inch by three inch rectangular ‘project box.’” Id.

After finding the claim term to be ambiguous, the district court determined that, in light of the prior art presented during litigation, the term “hand-grip size case” must be construed narrowly to sustain the patent’s validity. Id. From the extrinsic evidence presented at the Markman hearing, the court found that “the term ‘hand-grip’ cannot be construed so broadly as to encompass test devices contained in pocket-size cases.” Id.

Based upon its narrow claim construction, the district court ruled non-infringement.

In overturning the district court, the CAFC shed the complications.

Kapusta asserts that the district court erred in construing the claim term “hand-grip size case” to require the limitations that the case be “no smaller than the width of an adult palm, so that it can be grasped firmly in one’s hand, no smaller than 1 inch in width, and of a rectangular shape.” Kapusta contends that the court should have given the term its ordinary and customary meaning of “a case that is suited to a grip by the hand,” and the court should not have added limitations for which there is no support in the intrinsic record. With respect to the “of a rectangular shape” limitation, Kapusta argues that the district court imported a limitation from the preferred embodiment of the specification into the claims. Furthermore, Kapusta argues that the district court erred by finding the term at issue to be ambiguous and then importing unnecessary limitations in order to preserve the patent’s validity.

We agree with Kapusta that the district court erred in its claim construction by including extraneous limitations. The court should have given the term “hand-grip size case” its ordinary and customary meaning. See Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996) (explaining that unless the intrinsic evidence compels a contrary result, a claim term should be given its ordinary and customary meaning). The ordinary and customary meaning of “hand-grip size case” is a case of a size that can be gripped in a normal hand. We see no reason to depart from that ordinary and customary meaning or to add dimensions to the term, as there is no support for the district court’s limitations in the intrinsic record.

Finally, the court’s finding that the term is ambiguous and should be construed to sustain its validity is without basis. The term “hand-grip size case” is not ambiguous. Although the term may be of a nonspecific size and shape, that does not render the claim term ambiguous. Because the term is not ambiguous, the district court should not have applied the doctrine of construing claims to preserve their validity. Construing claims to sustain their validity has been limited to those cases in which “the court concludes, after applying all the available tools of claim construction, that the claim is still ambiguous.” Phillips, 415 F.3d at 1327 (quoting Liebel-Flarsheim Co. v. Medrad, Inc., 358 F.3d 898, 911 (Fed. Cir. 2004)). We have not applied the doctrine broadly and have “certainly not endorsed a regime in which validity analysis is a regular component of claim construction.” Phillips, 415 F.3d at 1327. This is not one of those limited cases where the term cannot be construed using other available tools. Had the district court limited its construction to the ordinary and customary meaning, it would not have had to resort to construing the claim term more narrowly to preserve its validity.

Case remanded for determining infringement based upon the obvious claim construction.