Credentials, Agrément, and the Vienna Framework

The legal architecture

The appointment of a head of mission is governed by Article 4 of the Vienna Convention on Diplomatic Relations (VCDR), opened for signature on 18 April 1961 and in force from 24 April 1964. Article 4(1) requires the sending State to ascertain that agrément has been given by the receiving State before nominating an ambassador, high commissioner, nuncio, or chargé d'affaires en pied. Article 4(2) is categorical: the receiving State is not obliged to give reasons for refusal. The companion provision, Article 7, preserves the sending State's free choice of other members of the diplomatic staff, subject to Articles 5, 8, 9, and 11 (multiple accreditation, nationality, persona non grata, and size of mission).

Agrément is requested confidentially through diplomatic channels — typically by the sending State's foreign ministry instructing its current chargé to deliver a note verbale to the receiving State's protocol directorate, accompanied by a curriculum vitae (the biographic note). The transaction is never publicized until acceptance is confirmed, because a leaked refusal embarrasses both governments. Processing times vary: the United States Department of State customarily replies within four to six weeks; the People's Republic of China and the Russian Federation have at times taken six months or longer when bilateral relations are strained.

Refusals and their political meaning

Refusal of agrément is rare but consequential. In 2010, Caracas declined Larry Palmer as U.S. ambassador after his Senate testimony on Venezuelan military morale; Washington retaliated by revoking the visa of Ambassador Bernardo Álvarez Herrera. In 2016, Beijing reportedly withheld agrément for several months on a proposed Mongolian ambassador following the Dalai Lama's visit to Ulaanbaatar. The 1891 Italian incident over Baron Fava and the 1885 U.S. refusal to accept Anthony Keiley (whom both Italy and Austria-Hungary rejected for his wife's religion and his anti-Italian speeches) are the textbook nineteenth-century precedents and remain cited in protocol manuals.

Because Article 4(2) requires no reasons, sending States typically withdraw the candidate quietly rather than provoke a public refusal. Foreign ministries maintain a short list precisely to permit substitution without delay. A pre-sounding — an informal inquiry by the chargé before any formal note — is the standard prophylactic against embarrassment.

Functional consuls and special envoys

The VCDR framework applies to diplomatic missions; consular officers are governed by the parallel 1963 Vienna Convention on Consular Relations (VCCR). Under VCCR Article 12, a consul requires an exequatur from the receiving State rather than agrément, and Article 23 provides the analogous power to declare a consul non acceptable. Special envoys, roving ambassadors, and ad hoc representatives fall under the 1969 Convention on Special Missions, which in Article 8 requires the receiving State's prior consent to the persons the sending State proposes to send, and under Article 17 permits refusal without explanation.

Multiple accreditation under VCDR Article 5 — where one ambassador covers several receiving States — also requires that each receiving State be notified and raise no objection. The Holy See's nuncios, Commonwealth high commissioners (governed by the 1952 London Declaration and bilateral practice rather than VCDR letter, though substantively equivalent), and the European Union's heads of delegation since the 2010 European External Action Service decision all operate within variant accreditation regimes that practitioners must distinguish.

Letters of credence

Once agrément is given, the sending head of State signs a Letter of Credence (lettres de créance) addressed personally to the receiving head of State. The instrument is in formal diplomatic French or the sending State's official language, identifies the bearer by name and rank, requests that full faith and credit be given to communications made on the sending State's behalf, and is countersigned by the foreign minister. A parallel Letter of Recall for the predecessor is prepared simultaneously and presented in the same ceremony. Chargés d'affaires en pied carry a Letter of Introduction signed by the foreign minister and addressed to the receiving foreign minister — a lower instrument reflecting their lower rank under VCDR Article 14.

Upon arrival, the new ambassador first calls on the chief of protocol and presents a true copy of the credentials. This copy presentation, governed by VCDR Article 13(1), is the operative moment at which the head of mission "is considered as having taken up his functions" in many receiving States — including France, Germany, and most Commonwealth jurisdictions — provided the receiving State's practice is uniform under Article 13(2). Other States, notably the United States, treat the formal ceremony with the President as the moment of function. The distinction matters for precedence: VCDR Article 16(1) orders heads of mission within each class by the date and hour of taking up functions.

The presentation ceremony

The formal ceremony is the visible apex of accreditation. Practice varies but follows a common skeleton: the chief of protocol collects the ambassador from the residence in a State car; a military escort accompanies the motorcade; the ambassador is received by the head of State, hands over both the Letter of Credence and the Letter of Recall, exchanges brief remarks (in some capitals — Tokyo, London, Madrid — the remarks are formally exchanged in writing rather than spoken), and is then photographed. The Court of St James's preserves the horse-drawn Royal Mews carriages for ambassadors to the United Kingdom; the Élysée preserves the Garde républicaine honor guard; Washington dispenses with ceremony almost entirely, batching presentations in the Oval Office.

Between arrival and ceremony — sometimes weeks, occasionally months — the ambassador is restricted. By convention, an ambassador who has presented only a copy may conduct business with the foreign ministry but does not call on the head of State, other ambassadors, or attend functions in full diplomatic capacity. The dean of the diplomatic corps (the longest-serving ambassador, or in Catholic-tradition States the apostolic nuncio under the 1815 Congress of Vienna Règlement as preserved by VCDR Article 16(3)) does not formally call until after the ceremony.

Termination

Functions end under VCDR Article 43 by notification of the sending State that functions have come to an end, or by notification of the receiving State under Article 9 that the agent is persona non grata. The latter — which the receiving State may declare "at any time and without having to explain its decision" — is the symmetric counterpart to Article 4(2) refusal of agrément. The 2018 expulsions following the Salisbury poisoning, in which the United Kingdom expelled 23 Russian diplomats and 28 allied States expelled a further 130, remain the largest coordinated Article 9 action on record.