Previously, the substantially identical standard enunciated by 35 U.S.C. § 252 was analyzed in Aspex Eyewear, Inc., et al., v Marchon Eyewear Inc., et. al., (SDFLA). In the lower court ruling, the court found that claims changed/added in patent reexamination were in fact substantially identical to the previously issued claims. This was because, the claim changes made during patent reexamination added claim features the district court previously ruled to be embraced by the originally issued claim scope.
The lower court explained (decision here) that Aspex was barred from re-litigating these new claims against the previous defendants, reasoning:
The [previous action] was fully adjudicated on the merits. The dismissal release . . . made clear that the settlement dismissed with prejudice as to any causes of action “any claim which could have been had by and between the Parties arising from or connected with [the earlier dispute]. Plaintiffs argue that it alleged legally separate causes of action in their complaint because claim 23 and claim 35 [reexamination changes] did not exist at the time the [previous actions] were being litigated. The reexamination of the ‘545 Patent does not entitle Plaintiffs to circumvent claim preclusion because the amended claims relate back to the original ‘545 Patent reissue date. (emphasis added)
In affirming the lower court, the CAFC reasoned (decision here):
In arguing that the reexamination of the ’545 patent created new causes of action not barred by res judicata, Aspex relies on cases involving reissue patents. There are two problems with Aspex’s argument, however. First, as noted above, the two claims on which Aspex relies are not materially different from original claim 23, and thus they do not create a new cause of action that was not previously available to Aspex. Second, the differences between reissue and reexamination make the reissue cases on which Aspex relies inapposite. Unlike reissue, reexamination does not result in the surrender of the original patent and the issuance of a new patent. Moreover, by statute, new claims that emerge from reexamination must not be broader than the original claims. See 35 U.S.C. § 305 (“No proposed amended or new claim enlarging the scope of a claim of a patent will be permitted in a reexamination proceeding under this chapter.”); In re Freeman, 30 F.3d 1459, 1464 (Fed. Cir. 1994). Consistent with that rule, the claims on which Aspex relies are not broader than their predecessor; they therefore did not create a new legal right against infringement that Aspex lacked under the original version of the patent. Accordingly, claims that emerge from reexamination do not create a new cause of action that did not exist before. See Hoffman v. Wisner Classic Mfg. Co., 927 F. Supp. 67, 73 (E.D.N.Y. 1996). We therefore reject Aspex’s argument that the issuance of amended claim 23 and new claim 35 had the effect of negating the res judicata effect of the prior litigation . . . .
Interestingly, the applicaton of res judicata seems to hinge on the absence of the defense of intervening rights (due to the perceived sameness in the scope of claims before/after reexamination, a relatively uncommone set of circumstances). The second point relative to the patent surrender requirement of patent reissue seems to be more of the same. In other words, the impact of the surrender on the ability of the claims to “relate back” to the original patent for damage purposes will depend upon whether or not the claims were amended enough to trigger intervening rights (i.e., not substantially identical; 35 USC 252). The change in patent number for a patent reissue is of no moment.
As to the third point, while it is certainly true that claims cannot be enlarged in patent reexamination, they can be amended to undermine non-infringement (e.g., Markman definitions) positions of a defendant. As such, narrower claims, may greatly aid an infringement case and opportunities may in fact be created via patent reexamination that may not have existed previously.