In its December 14, 2012 opinion, the Federal Circuit affirmed the district court's decision that the Defendants did not prove that the patent was unenforceable due to inequitable conduct. Rather, the court found that while Shionogi employees made deliberate decisions to withhold material references from the USPTO during the prosecution of the original '440 patent application from which the '314 patent was reissued, the plaintiffs did not establish deceptive intent.

The Federal Circuit pointed out that there had been extensive live evidence before the district court, including testimony from the two employees accused of inequitable conduct. The Federal Circuit affirmed the district court finding that the Defendants failed to establish that either of the Shionogi employees withheld the references at issue with deceptive intent. The Federal Circuit reaffirmed that although deceptive intent may be inferred from circumstantial evidence under Therasense, Inc. v. Becton, Dickinson & Co., the inference must be the single most reasonable inference one could draw from the evidence. The Federal Circuit refused to reassess the district court's finding that deceptive intent was not the single most reasonable inference. The district court reached this finding based on its evaluation of the employees' credibility during testimony which showed that:

Turning to the issue of whether the '314 patent was improperly reissued, the Federal Circuit addressed the defendants' contention that Shionogi deliberately presented a claim in the '440 patent that overlapped the prior art to attempt to gain greater patent protection. The district court found that Shionogi did not intentionally create the error for which it sought reissue, citing, among other evidence, confusion, limited personnel, inexperience and lack of legal training in the Shionogi Patent Department.

In affirming the district court, the Federal Circuit, notably, rejected the Defendants' argument that deceptive intent in the reissue statute requires less rigorous proof than deceptive intent in connection with inequitable conduct. The court also noted that the reissue application was promptly filed upon discovery of the error.

On the issue of patent infringement, defendant Apotex argued that it did not "submit" the ANDA within the meaning of Section 271(e)(2)(A) of the Patent Act because it merely signed and filed the ANDA on behalf of its Canadian affiliate, and therefore it cannot infringe the US patent. To support its position Apotex claimed that the parent-subsidiary relationship, agency principles or intent to benefit from an ANDA are not relevant factors in determining whether an entity is a submitter under the Hatch-Waxman Act.

The Federal Circuit held that the district court did not err in holding that Apotex was properly named as a defendant and affirmed the judgment of infringement. The Federal Circuit noted that lower courts have applied liability to the ANDA "submitter" who signs the ANDA and intends to directly benefit from the ANDA. In this case, Apotexintended to sell the drug in the US.