In diplomacy, the term persona non grata, literally meaning "person not appreciated", refers to a foreign person whose entering or remaining in a particular country is prohibited by that country's government.
Diplomacy is the art and practice of conducting negotiations between representatives of states.
"Persona Non Grata" - trailer by FCPoland
It is the most serious form of censure which one country can apply to foreign diplomats, who are otherwise protected by diplomatic immunity from arrest and other normal kinds of prosecution.
Diplomatic immunity is a form of legal immunity that ensures diplomats are given safe passage and are considered not susceptible to lawsuit or prosecution under the host country's laws, although they can still be expelled.
An arrest is the act of depriving people of their liberty, usually in relation to an investigation or prevention of a crime, and thus detaining the arrested person in a procedure as part of the criminal justice system.
Persona Non Grata, explained - International Law Animation by LEX ANIMATA
Persona non grata can also refer to "A person without standing" in the matters at hand, legal or otherwise.