This Note addresses the three-way circuit split among the U.S. Courts of Appeals over when, and to what extent, a court may consider a defendant’s subjective intent in defining a “destructive device” under the National Firearms Act. The circuit split centers on the Act’s ambiguous reference to intent in its definition of a destructive device, which is a statutorily prohibited firearm. After discussing the Act’s legislative history and development, this Note considers the role of mens rea in National Firearms Act cases. It next addresses the disagreement among the Courts of Appeals, first detailing three cases that give rise to the disagreement and then discussing additional cases which support each position. Finally, this Note argues that the U.S. Court of Appeals for the Second Circuit’s view, espousing a generally objective approach and eschewing a consideration of a defendant’s intent outside of a small range of cases, is most consistent with legisl ative history, statutory interpretation, and common sense.