“Authentication” or “authentification”, in relation to a notarised document, is the process whereby a relevant local authority stipulates to the fact that the document notarized has in fact been notarised by a legitimate notary public, i.e. that that public notary has been duly sworn and admitted to practice as a notary and has the power and capacity to create notarial certificates or acts.
The relevant authority holds a database of all admitted public notaries practicing in the state and can therefore conclusively state whether or not an individual purporting to notarize a document is entitled to do so. In Australia this authority is most commonly the Department of Foreign Affairs and Trade. The process of authentication will usually take the form of the application of an “apostille” or the process of “legalisation“.
Because of the operation of the Hague Convention of 5 October 1961, whether an apostil or a legalization will be required will depend on what legal jurisdiction that notarised document is to be ultimately used (n.b. not all countries have signed or ratified the Convention).