In a recent memorandum opinion, Judge Leonard P. Stark ruled that a defendant was barred by issue preclusion from arguing that the patent at issue is invalid or unenforceable, under any theory, because the defendant’s parent company had controlled an affiliate’s earlier litigation which resulted in a ruling that the same patent was not invalid or unenforceable. Astrazeneca UK Ltd., et al. v. Watson Laboratories, Inc. (NV), et al., C.A. No. 10-915-LPS (D. Del. Nov. 14, 2012). The Court agreed with the plaintiffs that invalidity and unenforceability represent “single issues” for purposes of issue preclusion—such that the defendant was not only barred from litigating the same invalidity and unenforceability theories that the affiliate had argued unsuccessfully in the earlier litigation, but was barred from asserting any invalidity or unenforceability theories. Id. at 11-12. The Court rejected the plaintiffs’ argument, though, that another generic manufacturer and co-defendant was a proxy of the issue precluded defendant who also should be barred from arguing invalidity and unenforceability. Id. at 13-14.
The Court also considered the defendant’s motion for summary judgment of non-infringement under the doctrine of equivalents, which argued that “because the patentees used narrow claim language, Plaintiffs are precluded from relying on the doctrine of equivalents to expand the patent’s scope.” Id. at 4. The plaintiffs responded that “the doctrine of equivalents applies and protects patentees from infringers who make insubstantial changes to the claimed invention.” Id. The Court denied the motion without prejudice, finding that “the most appropriate course is to hear all of the evidence at trial and make a conclusion on the doctrine of equivalents thereafter.” Id. at 9.