In diplomacy, a persona non grata is a foreign person whose entering or remaining in a particular country is prohibited by that country's government. Being so named is the most serious form of censure that a country can apply to foreign diplomats who are otherwise protected by diplomatic immunity from arrest and other normal kinds of prosecution.
Diplomacy
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. So-called "tit for tat" exchanges have occurred, notably during the Cold War. A notable occurrence outside of the Cold War was an exchange between the United States and Ecuador in 2011: the Ecuadorian government expelled the United States ambassador, as a result of diplomatic cables leaking ; the United States responded by expelling the Ecuadorian ambassador. The most notable recent example was the backlash after the 2018 Novichok attacks in Salisbury. 146 Russian diplomats were expelled from 29 countries. In response the Russians expelled the same number of diplomats from each country, to which the U.K. recalled a further 27 of their diplomats.
Other usage
People other than diplomats can be declared as persona non grata by a country. In non-diplomatic usage, referring to someone as persona non grata is to say that the person is not popular or accepted by others.
