A brief by Cato director of health policy studies Michael F. Cannon and Case Western Reserve University law professor Jonathan H. Adler filed for the D.C. Circuit’s en banc consideration of Halbig v. Burwell. The brief provides new evidence from the Patient Protection and Affordable Care Act’s legislative history that confirms the Circuit panel’s conclusion that the Internal Revenue Service has no authority to issue “premium assistance tax credits” in states with federal Exchanges, and is violating the Act by doing so. The brief further illustrates how contrary interpretations by the panel’s dissent and the Fourth Circuit cannot be reconciled with the statute.