19 CFR 146.31: Admissibility of merchandise into a zone.

Merchandise of every description may be admitted into a zone unless prohibited by law. A distinction is made between prohibited and conditionally admissible merchandise.

(a) Prohibited merchandise. Port directors shall not admit prohibited merchandise. If there is a question as to whether the merchandise may be prohibited, port directors may permit the temporary deposit of the merchandise in a zone pending a final determination of its status. Any prohibited merchandise which is found within a zone will be disposed of in the manner provided for in the laws and regulations applicable to that merchandise.

(b) Conditionally admissible merchandise. The admission of this merchandise into a zone is subject to the regulations of the Federal agency concerned.