Vienna Convention on Diplomatic Relations

The Vienna Convention on Diplomatic Relations (VCDR) was adopted on 18 April 1961 at a UN conference in Vienna and entered into force on 24 April 1964. It is one of the most widely ratified treaties in the world, with nearly universal participation among UN member states, and is generally regarded as reflecting customary international law on diplomatic intercourse.

The Convention codifies long-standing practice governing how states establish and conduct permanent diplomatic missions. Key provisions include:

• Article 22: the premises of the mission are inviolable; host state agents may not enter without the head of mission's consent, and the host has a special duty to protect the premises against intrusion or damage.
• Article 24: the archives and documents of the mission are inviolable at any time and wherever they may be.
• Article 27: free communication for official purposes, including the protection of the diplomatic bag, which shall not be opened or detained.
• Articles 29–31: the person of a diplomatic agent is inviolable and immune from criminal jurisdiction, with limited civil and administrative immunity exceptions (e.g., private real property, succession, commercial activity outside official functions).
• Article 9: the host state may at any time declare a diplomat persona non grata, without giving reasons.
• Article 32: immunity may be waived, but only expressly and by the sending state, not the individual.

The VCDR distinguishes diplomatic from consular relations, which are governed by the separate Vienna Convention on Consular Relations (1963). It has been invoked in major disputes, including the ICJ's United States Diplomatic and Consular Staff in Tehran judgment (1980), where the Court found Iran in breach of its obligations under both Vienna Conventions following the 1979 seizure of the US embassy.

For Model UN delegates and researchers, the VCDR is the baseline reference whenever questions of embassy inviolability, expulsion of diplomats, or abuse of diplomatic privilege arise.