 Mallinckrodt plc NYSE: MNK, a global biopharmaceutical company, announced today that it will appeal a ruling by the U.S. District Court for the District of Columbia in a lawsuit filed by its subsidiary, Mallinckrodt ARD LLC, against the U.S. Department of Health and Human Services HHS and the Centers for Medicare and Medicaid Services CMS, regarding the Medicaid drug rebate calculation for Acthar Gel repository corticotropin injection. 