Claim Preclusion: The Focus of the “Material Differences” Test May Be on the Claim Limitations at Issue

Nystrom v. Trex Co., No. 2009-1026 (Fed. Cir. Sept. 8, 2009):

Holding:

The accused infringer may assert claim preclusion when the sole claim limitations at issue in the first suit remain unchanged in the second suit. Slip op. at 6-7.

Facts:

In the earlier case, the patentee sued the accused infringer for patent infringement and lost, during which the district court found that the patentee waived the doctrine of equivalents (DOE). In the present and second case, the patentee alleged that the accused infringer’s second generation products infringe the same patent under the DOE. The Court held that claim preclusion applies.

Judge Rader’s Additional Views

Judge Rader issued a separate opinion to present interesting and insightful additional views, explaining the differences between DOE and claim vitiation.

In short, Judge Rader explained that “the vitiation doctrine is really subsumed within the test for equivalents itself” because “the all elements rule is simply a circular application of the doctrine of equivalents.” Slip op. at 2. (J. Rader). The only difference is that “the identical equivalents and vitiation tests are made by different decision makers,” as the determination of equivalency is a question of fact, while application of the all elements rule (claim vitiation) is a question of law. Id. at 3.

Comments:

To apply claim preclusion, an accused infringer must show that the accused product or process in the second suit is “essentially the same” as the accused product or process in the first suit. Slip op. at 6.

Previously, the Court has emphasized that the focus for claim preclusion should be on “material differences” between the two accused devices, but has not addressed directly whether the focus of the “material differences” test is on the claim limitations at issue in each particular case. Slip op. at 7.

This case presents a slightly new angle because it presents the latter issue. The two “material differences” tests are really not that different. Indeed, “material differences” between the two accused devices may be further analyzed through “material differences” on the claim limitations at issue.

Note that the “colorable changes” do not alter the application of claim preclusion. In this case, the addition of wood grain or a change in color does not alter this limitation either in any way material to the infringement inquiry.

On another practical note, here, in the first case, the parties stipulated to non-infringement without reference to equivalents. As a result, the Court held that the patentee had waived the DOE argument. To avoid this pitfall, in the future, the parties should clearly indicate whether the DOE is waived when stipulating to non-infringement.