Context: 

A day after Canada announced it would expel a Chinese diplomat over allegations of involvement in a campaign to intimidate a Canadian politician, China declared a Canadian diplomat in Shanghai as persona non grata.

What is persona non grata?

• Persona non grata is a Latin phrase which means “unwelcome person.” 
• In diplomacy, it refers to a diplomat or foreign person whose entering or remaining in a certain country has been prohibited by that country.
• The designation received diplomatic meaning at the 1961 Vienna Convention for Diplomatic Relations. 
  • Article 9 of the treaty mentions that a country can declare any member of a diplomatic staff persona non grata at any time and without having to explain its decision.
• Soon after the declaration, the person concerned usually returns to their home nation. 
• In case they fail to do so within a reasonable period, the country “may refuse to recognise the person concerned as a member of the mission.” 
• A person can be declared persona non grata even before arriving in a country.

When is it used?

• There aren’t any fixed rules regarding when a country can declare a foreign person persona non grata as it doesn’t need to give an explanation according to Article 9 of the Vienna Convention.
• Historically, countries have used it to express their discontent with the actions of other nations. 
• During the Cold War, it became a “tit-for-tat” sanction as both the US and the Soviet Union liberally declared each other’s diplomats persona non grata.
• The imposition of persona non grata designation isn’t just limited to diplomats.

News Source: Indian Express