[For purposes of claim preclusion, where the claim interpretation of a particular term] is determinative of non-infringement . . . it is irrelevant whether the additional claims now in suit contain additional terms that were not previously construed.

On April 19, 2013, in Aspex Eyewear, Inc. v. Zenni Optical, LLC, the U.S. Court of Appeals for the Federal Circuit (Newman,* Prost, Reyna) affirmed the district court's ruling that prior litigation collaterally estopped Aspex Eyewear, Inc. from bringing suit alleging patent infringement by Zenni Optical, LLC, of U.S. Patents No. 5,737,054, No. 6,012,811 and No. 6,092,896, which related to magnetic rimless clip-on eyewear. The Federal Circuit stated:

Collateral estoppel "precludes a plaintiff from relitigating identical issues by merely switching adversaries" and precludes a plaintiff "from asserting a claim that the plaintiff had previously litigated and lost against another defendant." . . . To claim the benefit of collateral estoppel the par¬ty relying on the doctrine must show that: (1) the issue at stake is identical to the one involved in the prior proceeding; (2) the issue was actually litigated in the prior proceeding; (3) the determina¬tion of the issue in the prior litigation must have been 'a critical and necessary part' of the judgment in the first action; and (4) the party against whom collateral estoppel is asserted must have had a full and fair opportunity to litigate the issue in the prior proceeding. The district court found that each of these criteria is met. . . .

Aspex argues that the issues now at stake are different because some of the claims of the '896 patent that are asserted against Zenni were not asserted against [the defendant in the prior litigation,] Altair, although several claims were commonly asserted. The common claims are Claim 1 of the '054 patent, which is not at issue on appeal; Claims 1, 22, and 31 of the '811 patent; and Claims 13, 15, and 19 of the '896 patent. Aspex states that the newly-asserted claims contain limitations that were not previously construed and applied. However, every claim asserted against Zenni contains the same "retaining mechanism" limitation, in the same context, that the Federal Circuit in Altair III found dispositive of non-infringement. The Zenni and Altair products are materially identical. In such circumstances, the assertion of different claims in a subsequent suit does not create a new "issue" to defeat preclusion.

No changed circumstances are here shown, nor any new evidence nor materially different argument that was unavailable to Aspex in the Altair litigation. The Aspex claims now in suit contain the same "retaining mechanism" term that was construed in Altair as requiring rims. This construction is determinative of non-infringement by the Zenni eyewear; it is irrelevant whether the additional claims now in suit contain additional terms that were not previously construed. A full and fair opportunity to litigate is the touchstone of any preclusion analysis. The "desire not to deprive a litigant of an adequate day in court" is balanced against the "desire to prevent repetitious litigation of what is essentially the same dispute."

The selection of additional claims for litigation and additional terms for "construction" does not override the holding of non-infringement. In determining whether Aspex had a full and fair opportunity to litigate the dis¬positive claim limitations in the prior proceeding, "[i]t is the issues litigated, not the specific claims around which the issues were framed, that is determinative. Only by focusing on the issues, and examining the substance of those issues, can the second court ascertain whether the patentee had the requisite full and fair chance to litigate . . . in the first suit."

The record shows that Aspex fully litigated the meaning of the term "retaining mechanism" in the first suit, and that it was finally adjudicated that "retaining mechanism" as used in these patents requires a rim around the lens, which resulted in a finding of non-infringement. Although Aspex argues that the terms "primary frame," "auxiliary frame," "first frame," and "second frame" were not at issue and therefore were not construed in the Altair litigation, the issues of infringement are not distinguished.

The district court correctly defined the issue as infringement by magnetic rimless clip-on eyewear in view of the final construction of "retaining mechanisms" as requiring rims. The court correctly found that Aspex had a full and fair opportunity to litigate this issue. We thus affirm that Aspex is collaterally estopped from relitigating infringement of these patents against these Zenni products.