The Constitution of the Universal Postal Union is the fundamental Act containing the organic rules of the Union. It is a diplomatic Act, ratified by the competent authorities of each member country. Amendments to it can be made only at Congress and are recorded in an Additional Protocol, which is also subject to ratification.
The common rules applicable to the international postal service and the provisions concerning the letter-post and parcel-post services are given in the Convention and its Regulations. The Regulations of the Convention are agreements concluded by the member countries elected by the Congress to the Postal Operations Council (POC). The POC has the authority to amend the Regulations at its annual sessions. The Convention and its Regulations are binding on all member countries.
The Postal Payment Services Agreement and its Regulations are binding only on the countries that are parties to the Agreement.
Models for ratification, approval or accession to the Acts
Member countries which did not sign the Acts adopted at the Istanbul Congress have an obligation to accede to them as soon as possible.
In accordance with article 26 of the UPU Constitution, the instruments of ratification of the Constitution and the Additional Protocols thereto and, where appropriate, of approval of the other Acts of the Union must be deposited as soon as possible with the Director General of the International Bureau.