50 U.S.C. § 224: Refusing clearance to vessels with suspected cargoes; forfeiture for departing without clearance

The Secretary of the Treasury is authorized to refuse a clearance to any vessel or other vehicle laden with merchandise, destined for a foreign or domestic port, whenever he shall have satisfactory reason to believe that such merchandise, or any part thereof, whatever may be its ostensible destination, is intended for ports in possession or under control of insurgents against the United States; and if any vessel for which a clearance or permit has been refused by the Secretary of the Treasury, or by his order, shall depart or attempt to depart for a foreign or domestic port without being duly cleared or permitted, such vessel, with her tackle, apparel, furniture, and cargo, shall be forfeited.