The U.S. Court of Appeals for the Federal Circuit, in an appeal involving multiple summary judgment motions, vacated the district court’s claim construction of the term "rear end" as recited in connection with a caulking tube and remanded the case for further proceedings. Research Plastics, Inc. v. Federal Packaging Corp., Case No. 04-1605 (Fed. Cir. Aug. 18, 2005) (Gajarsa, J.).
Research is the owner of U.S. Patent No. 5,628,433 (the `433 patent) directed at the "placement of ribs on the interior surface of a [caulking] tube" that "permit air to escape when a plunger is inserted into the bottom" of the tube filled with caulk or other material. The problem of trapped air in the tube was previously solved by using an air tap or bleed wire. That solution was considered "unduly complicated" and led to the specific ribs disclosed by the `433 patent that are used to "burp" the tube during the filling process.
Federal’s accused product included "a rear edge of the tube’s interior wall [that] tapers towards the outer wall forming a beveled edge. The exterior wall is longer than the interior wall, and so the diameter of the tube widens towards the back edge." The tube has ribs that are positioned "some distance" from the rear edge of the tube but in the rear half of the tube.
Both asserted claims include the term "rear end." The district court, after considering the claim language as well as the supporting specification, construed the term to mean "the edge of the tube as opposed to merely the rear portion of the tube." The edge, as interpreted by the lower court, meant the outermost edge of the tube. Based on this construction the district court granted Federal’s motion for summary judgment of non-infringement. Research appealed.
The Federal Circuit vacated the summary judgment of non-infringement, holding the term "rear end" was misconstrued by the district court. The Court held that properly construed, the claim term "rear end" referred to the entire rear edge of the tube, including the points at the rear end of the tube both inside and outside and the area in between, not just the point on the outside of the rear edge.
The Federal Circuit relied on the intrinsic claim construction evidence, first considering the claim language itself. The Court reasoned using the language of one claim may help interpret the other claim, applying a principle enunciated in the recent en banc Phillips decision: "the usage of a term in one claim can often be used to illuminate the meaning of the same term in another claim." The written description and the prosecution history were also cited as supporting the Court’s interpretation. The Court remanded to the district court to reconsider the issue of literal infringement under the new construction, while noting Research is precluded from relying on the doctrine of equivalents as it had narrowed the claims during prosecution with regard to the location of the ribs.
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