In United States v. Burwell, the United States Court of Appeals for the District of Columbia Circuit reviewed en banc the question of whether the Government must prove that the Defendant knew of the firearm’s automatic capability before invoking 18 U.S.C. § 924(c)(1)(B)(ii)’s mandatory thirty-year minimum sentence. The majority affirmed the Defendant’s conviction, holding that the D.C. Circuit’s previous holding in United States v. Harris determined that no mens rea applies to the machinegun provision. The dissenting opinion, however, argued that the Supreme Court’s decision in United States v. O’Brien, in which the Court held that the automatic capability of the firearm was an element of the offense, calls for the mens rea presumption to extend to that element. This Comment explains the differences in interpretation of the mens rea presumption between the majority and dissent, and argues that the dissenting opinion more accurately reflects the fundamental principles of the mens rea presumption.