Legalization is indispensable for a foreign public document to be valid in Italy.
It consists only of the official certification - by the competent Italian consular or diplomatic authority abroad – of the legal status of the public official (or functionary) who has signed the document and the authenticity of his signature. If the document is issued by a foreign authority in Italy, it must be legalized by the Prefect in the district in which the foreign authority is located (except for the Aosta Valley, where this is a responsibility of the President of the Region, and the Provinces of Trento and Bolzano, where it is the responsibility of the Government Commissioner). Legalization, on the other hand, does not guarantee the validity or force of the document in its country of origin, and in this sense it is much less than a notarial certification, in that legalization (like an apostille) entails no check on or acceptance of the content of the document.
Lack of legalization, then, means that the document (though valid and with legal force in its country of origin) is not legally valid in Italy and may not be used by a notary.
In particular, a foreign public document is not valid as such but merely as an unauthenticated private document.
If an Italian document must be used abroad, legalization – if requested by the foreign authorities – must be done by the Procurator of the Republic at the Tribunal in whose jurisdiction the notary is located who receives or authenticates the document. The signature of the Procurator of the Republic, in its turn, is legalized by the foreign Consulate responsible for that locality.
This is stipulated in Articles 30-31-33 of Presidential Decree no. 445 of 28/12/2000, which came into force on 7 March 2001.
Legalization is not necessary when the country from which the foreign public document was issued is a signatory to the Hague Convention of 5/10/1961 regarding apostilles, or a bi- or multi-lateral international convention that obviates the need for it. The Brussels Convention of 1987 on the exemption from apostilles in relations among countries of the European Union has not yet been ratified by all countries in the Union, and is therefore in force only among a number of them (for now only in Belgium, Denmark, France, Ireland and Italy).