The Fourth Circuit affirmed a District of Maryland decision to dismiss False Claims Act claims against Allergan Sales LLC under Rule 12(b)(6). The relator alleged that Allergan had violated the Medicaid Drug Rebate Program by providing false reports to the government of the “best price.” The Fourth Circuit held for Allergan, finding that the company had interpreted “best price” reasonably as the lowest price at which the company sells the drug in the United States, and that Allergan was not “warned away” from that interpretation by CMS guidance. Therefore, the relator’s complaint failed to allege facts to show that Allergan had knowingly defrauded the Medicaid Drug Rebate Program.