Code of Federal Regulations Title 19. Customs Duties § 19.12.104h Exempt materials and articles

(1) Has been held in the U.S. for a period of not less than 3 consecutive years by a recognized museum or religious or secular monument or similar institution, and was purchased by that institution for value, in good faith, and without notice that such material or article was imported in violation of these regulations, but only if—

(2) If paragraph (b)(1) of this section does not apply, has been within the U.S. for a period of not less than 10 consecutive years and has been exhibited for not less than 5 years during such period in a recognized museum or religious or secular monument or similar institution in the U.S. open to the public;

(3) If paragraphs (b)(1) and (2) of this section do not apply, has been within the U.S. for a period of not less than 10 consecutive years and the State Party concerned has received or should have received during such period fair notice (through such adequate and accessible publication, or other means, as the Secretary or his designee shall prescribe) of its location within the U.S.;  and

(4) If none of the preceding subparagraphs apply, has been within the U.S. for a period of not less than 20 consecutive years and the claimant establishes that it purchased the material or article for value without knowledge or reason to believe that it was imported in violation of law.