As Congress is given exclusive power of legislation over the District of Columbia and " places purchased by the consent of the legislature of the state in which the same shall be, for the erection of forts, magazines, arsenals, dockyards, and other needful buildings (Const. Art. I, § 8, ¶ 17), it may provide for the punishment of all crimes committed within such district or within such places, as fully as a state may provide for the punishment of crimes within its own limits. Congress has therefore adopted a general criminal code for the definition and punishment of offences within such district and places. Even though the states may retain the right to issue criminal process into such places they have no authority to punish crimes committed there, for the jurisdiction of the United States is exclusive. (See below, § 107.)