There are different routes to pariah status. North Korea, with its gross human rights abuses and illicit nuclear weapons programme tops the list and represents the classic pariah - completely ostracized from the international system. Another sure-fire way to become a pariah is to sponsor international terrorism, like Muammar Gaddafi’s Libya in the 20th century. But as his example shows, international rehabilitation can happen almost overnight. Then there are less clear cut pariahs like Zimbabwe, condemned by the West but very much part of the regional African system. Four expert witnesses examine these cases and explore whether the notion of a pariah state is meaningful in the 21st century multi-polar world. Presenter: Kavita Puri Producer: Lucy Proctor

(Photo: Ostracized /Getty Images)