(a) General rule. A person who seeks to enter, or cause to be entered, an article shall obtain a license, in accordance with this subpart, except as provided in paragraph (b).
(b) Exceptions. Licenses are not required if:
(1) The article is imported by or for the account of any agency of the U.S. Government;
(2) The article is imported for the personal use of the importer, provided that the net weight does not exceed five kilograms in any one shipment;
(3) The article imported will not enter the commerce of the United States and is imported as a sample for taking orders, for exhibition, for display or sampling at a trade fair, for research, for testing of equipment; or for use by embassies of foreign governments. Written approval of the Licensing Authority shall be obtained prior to entry, and the importer of record (or a broker or agent acting on its behalf) shall provide to the Licensing Authority, prior to the release of such articles, the appropriate Customs documentation identifying the article, quantity to be imported, its location, intended use, an entry number and the importer of record. The Licensing Authority may also require as a condition of import that the article be destroyed or re-exported after such use; or
(4) Such person pays the applicable over-quota rate of duty.