A second-level state authority — typically the Secretary of State or the U.S. Department of State — verifies the signature of the first-level authority. This process is known as apostille or legalization, depending on the destination country.
In the United States, the procedure varies depending on whether the receiving country is a party to the Hague Apostille Convention. For countries that have signed the Convention, the Secretary of State in the state where the document was issued provides the apostille. For countries that have not signed the Convention, additional steps are required: the document must first be authenticated by the U.S. Department of State in Washington, D.C., and then legalized by the embassy or consulate of the destination country.
This two-step system ensures that U.S. documents are properly validated for international use, whether through apostille or full consular legalization.