categories of diplomatic representation developed over the years of diplomatic practice and recognized by international law.
A uniform classification for diplomatic representatives was introduced by the Treaty of Vienna of 1815 and the supplementary protocol signed in Aix-la -Chapelle (Aachen) in 1818. The classification comprised the following classes: (1) ambassadors, legates, and nuncios, (2) envoys extraordinary and other persons accredited to the head of state, (3) ministers resident, and (4) chargés d’affaires. The privileged position of diplomatic representatives of the first class was established at this time. Initially only the great powers, the members of the Holy Alliance, had the right to appoint ambassadors.
During the 19th and early 20th centuries, the distinction between ambassadors and envoys gradually was eliminated and the class of ministers resident disappeared entirely. The Vienna Conference of 1961 on diplomatic relations and immunities established a new class system for diplomatic representatives. According to article 14 of the Vienna Convention, the heads of missions are divided into three classes: (1) ambassadors and nuncios accredited to the heads of states, and other heads of missions of equivalent rank, (2) envoys and internuncios accredited to the heads of states, and (3) chargés d’affaires accredited to the ministries of foreign affairs.
As a rule, states exchange diplomatic representatives of the same class; the class is determined by agreement between the states. In practice, accreditation of ambassadors predominates. Permanent chargés d’affaires are usually appointed when relations between states are not well developed or are deteriorating. Contemporary international law does not recognize any distinction between the heads of diplomatic missions of the same or different classes other than distinctions of seniority and etiquette.
The service rank of a diplomatic representative is technically distinct from the diplomatic class of the mission; however, as a rule they coincide in practice. Diplomatic ranks are regulated according to the domestic law of each state.
I. P. BLISHCHENKO