In diplomacy, a chargé d'affaires (French for "charged with (in charge of) matters"), often shortened to simply chargé, is a diplomat - usually a diplomatic Secretary, Counselor or Minister - who heads a diplomatic mission (e.g., an Embassy) in the absence of its titular (e.g., an Ambassador).
A chargé d'affaires represents his or her nation in the country they are accredited to, and enjoy the same privileges and immunities of a regular Ambassador. In most cases, a chargé would only serve as a chargé d'affaires ad interim, heading the diplomatic mission on a temporary basis in the absence of the ambassador. However, in unusual situations, a chargé d'affaires en pied may be appointed for an indefinite period of time.
Chargés d'affaires 
Chargés d'affaires (ministres chargés d'affaires), who were placed by the règlement of the Congress of Vienna in the fourth class of diplomatic agents, are heads of permanent missions accredited to countries to which, for some reason, it is not possible or not desirable to send agents of a higher diplomatic rank (although the countries maintain diplomatic relations).
In certain cases, a chargé d'affaires may be appointed for long periods of time, such as when a mission is headed by a non-resident ambassador who is accredited to multiple countries. In addition, a mission may be downgraded from an ambassadorial to a chargé d'affaires level in order to show displeasure, yet avoid taking the extremely serious step of breaking diplomatic relations. For example, Saudi Arabia and Thailand have not exchanged ambassadors since 1989, due to the still-unresolved Blue Diamond Affair.
When diplomatic recognition is extended to a new government, a chargé will be sent to immediately establish diplomatic representation. However, if a timely exchange of ambassadors does not take place, this may result in a prolonged period of chargé-level relations. For example, the United Kingdom recognized the People's Republic of China in 1950 and posted a chargé d'affaires in the new capital of Beijing. However, China was unwilling to exchange ambassadors until the United Kingdom withdrew its consulate from Taipei. Sino-British relations were not upgraded to the ambassadorial level until 1972.
Since a chargé d'affaires does not need to present letters of credence to the host head of state, appointing a chargé may avoid a politically sensitive meeting that would imply some form of approval or recognition of that head of state or government. Equally, the receiving country may decline to receive an ambassador, but maintain diplomatic relations by accepting a chargé. For example, the Republic of Cyprus appoints a number of chargé d'affaires en pied to its embassies abroad.
Chargés d'affaires en pied are distinguished from chargés d'affaires ad interim by the fact that their credentials are addressed by the foreign minister of the state they represent to the foreign minister of the receiving state. They have precedence over chargés d'affaires ad interim.
Chargés d'affaires ad interim 
Chargés d'affaires ad interim are those who temporarily head a diplomatic mission in the absence of the accredited head of that mission. They are presented as such, either orally or in writing, by heads of missions of the first, second or third rank to the minister for foreign affairs of the state to which they are accredited, when they leave their post temporarily, or pending the arrival of their successor. It is usual to appoint a counsellor or secretary of legation to be chargé d'affaires. Some governments are accustomed to give the title of minister to such chargés d'affaires, which ranks them with the other heads of legation.
In modern use, chargés d'affaires do not essentially differ from ambassadors, envoys or ministers resident. They represent their nation, and apart from rank and precedence, enjoy the same privileges and immunities as other diplomatic agents.
However, there have been rare historical circumstances in which a diplomatic post, formally ranking as chargé d'affaires, was in fact employed in a more significant colonial role, as commonly held by a Resident. Thus, in Annam-Tonkin (most of present Vietnam), the first French chargé d'affaires at Huế, the local ruler's capital, since 1875; one of them (three terms) was appointed the first Resident-general on 11 June 1884, as they stopped being tributary to the Chinese empire, less than a year after the 25 August 1883 French protectorates over Annam and Tonkin (central and northern regions).
In French usage, chargé d'affaires may be used outside diplomacy either as a specific position, or in general terms to indicate an individual with some more or less temporary responsibility for a specific area of activity.
Spelling and grammar 
Chargé d'affaires generally follows French usage: chargé d'affaires is singular, chargés d'affaires for plural. The "d'affaires" is always in the plural form, and should be lowercase even if Chargé is capitalized. Although non-standard and unusual, chargée d'affaires (with the feminine ending) may be seen where the chargé is female.
For temporary chargés, ad interim may or may not be added depending on the context, but is always lower case; it may be italicized or shortened to simply a.i.
References and footnotes 
- "13 March 1972". Parliamentary Debates (Hansard) (House of Commons). 13 March 1972
- "Cyprus Diplomatic Missions Abroad". Retrieved 19 May 2013.
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.
- eDiplomat.com: Glossary of Diplomatic Terms
- WorldStatesmen-Italian states to 1860