Persona non grata
The government of a country can declare a diplomat persona non grata, banning their entry into that country. In non-diplomatic use, the authorities of a country may also declare a foreigner persona non grata permanently or temporarily, usually because of unlawful activity.
In diplomacy, a persona non grata (Latin: "person not welcome", plural: personae non gratae) is a status sometimes applied by a host country to foreign diplomats to remove their protection by diplomatic immunity from arrest and other normal kinds of prosecution.
Under Article 9 of the Vienna Convention on Diplomatic Relations, a receiving state may "at any time and without having to explain its decision" declare any member of a diplomatic staff persona non grata. A person so declared is considered unacceptable and is usually recalled to his or her home nation. If not recalled, the receiving state "may refuse to recognize the person concerned as a member of the mission"
A person can be declared a persona non grata before that person even enters the country.
With the protection of mission staff from prosecution for violating civil and criminal laws, depending on rank, under Articles 41 and 42 of the Vienna Convention, they are bound to respect national laws and regulations. Breaches of these articles can lead to a persona non grata declaration being used to punish erring staff. It is also used to expel diplomats suspected of espionage, described as "activities incompatible with diplomatic status", or any overt criminal act such as drug trafficking. The declaration may also be a symbolic indication of displeasure.
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