Whenever entry of any imported merchandise is not made within the time provided by this Chapter, or whenever, in the opinion of the Collector, entry of such merchandise cannot be made for want of proper documents or other cause, he shall take the merchandise into his custody, to be held at the risk and expense of the consignee until entry is made or completed and the proper documents are produced, or a bond given for their production.
At the request of the consignee of any merchandise, or of the owner or master of the vessel in which the same is imported, any merchandise may be taken into possession of the Collector after the expiration of one day after the entry of the vessel and may be unladen and held at the risk and expense of the consignee until entry thereof is made.

SOURCE: GC § 47117.