18 U.S.C. § 16 : US Code - Section 16: Crime of violence defined

      The term "crime of violence" means - 
        (a) an offense that has as an element the use, attempted use,
      or threatened use of physical force against the person or
      property of another, or
        (b) any other offense that is a felony and that, by its nature,
      involves a substantial risk that physical force against the
      person or property of another may be used in the course of
      committing the offense.