(a) The provisions of the Act and these regulations shall not apply:
(1) To any marine mammal taken before December 21, 1972, or
(2) To any marine mammal product if the marine mammal portion of such product consists solely of a marine mammal taken before such date.
(b) The prohibitions contained in § 18.12(c) (3) and (4) shall not apply to marine mammals or marine mammal products imported into the United States before the date on which notice is published in the Federal Register of the proposed rulemaking with respect to the designation of the species of stock concerned as depleted or endangered:
(c) Section 18.12(b) shall not apply to articles imported into the United States before the effective date of the foreign law making the taking or sale, as the case may be, of such marine mammals or marine mammal products unlawful.