The President negotiates and ratifies treaties and international agreements (Article 55 of the Constitution). He is informed of all negotiations pertaining to the conclusion of an international agreement not subject to ratification. Ratification or the approval of treaties of alliance, treaties of commerce, treaties or agreements relating to international organizations, of those that invest state finances, those that amend the legislative provisions, those concerned with the status of persons, peace treaties, and those that incorporate territory modification must be authorized by law and therefore ratified by the parliament (Article 82.3 of the Constitution).

Before all ratification, treaties are submitted by the President for the control of the constitutionality of the High Constitutional Court. In the event of non-conformity with the Constitution, no ratification may take place except after it revision. From the moment of their ratification, treaties or agreements that are ratified or approved regularly have authority over and above that of the law, without reserve, for the use of each agreement or treaty by the other party.