The process for authenticating a U.S. state-issued document for use abroad depends on whether the requesting country is party to the Hague Convention Abolishing the Requirement of Legalization for Foreign Public Documents. The Convention, to which both Ireland and the U.S. are party to, abolished the requirement of diplomatic and consular legalization of public documents originating in one Convention country intended for use in another Convention country.
To authenticate U.S. state-issued documents for use in Ireland and in other Hague countries:
Such documents include birth, death, and marriage certificates, documents executed before a U.S. notary public, and credentials bearing the seal of a college or university.
An authentication or Apostille (meaning ‘certification’) must be obtained from the Secretary of State for the U.S. state in which the documents were originally issued. Please be advised the U.S. Embassy does not have the authority to issue an Apostille or a letter of authentication.
Contact the Secretary of State in the state in which the state-issued document was issued for further information on the process involved. For a list of Secretaries of State, please visit: http://www.hcch.net/index_en.php?act=authorities.details&aid=353
If you require an Apostille for use in a Non-Hague country: https://travel.state.gov/content/travel/en/legal/travel-legal-considerations/internl-judicial-asst/authentications-and-apostilles/office-of-authentications.html