22 CFR §92.39

1. (a)A copy of a foreign public document intended to be used as evidence within the jurisdiction of the Federal Government of the United States must be authenticated in accordance with the provisions of section 1 of the act of June 25, 1948, as amended (sec. 1, 62 Stat. 948, sec. 92(b), 63 Stat. 103; 28 U.S.C. 1741). This provision of Federal law provides that a copy of any foreign document of record, or on file in a public office of a foreign country or political subdivision thereof, if certified, by the lawful custodian thereof, may be admitted in evidence when authenticated by a certificate of a United States consular officer resident in the foreign country, under the seal of his office.
2. (b)The consular officer's certificate should indicate that the copy has been certified by the lawful custodian.
3. (c)In the absence of a consular officer of the United States as an officer resident in the State of the Vatican City, a copy of any document of record or on file in a public office of said State of the Vatican City, certified by the lawful custodian of such document may be authenticated by a consular officer of the United States resident in Rome, Italy (22 U.S.C. 1204).