'Expulsion' is an act, or a failure to act, by a State with the intention and the effect of securing the departure of a person or persons against their will from the territory of that State. The concept of expulsion encompasses indirect measures including ill-treatment, racial and other forms of discriminatory practices, harassment and other means of coercion designed to force people to leave—as well as the direct exercice of State power. Forms of indirect measures or practices are many and are sometimes of a subtle kind. These can be of a psychological as well as of an economic or social nature. In some cases, the authorities of a State tolerate, or even aid and abet, acts by its citizens with the intended effect if driving persons out of the territory of that State. An example is 'panic flight' where, for the purpose of removing the persons concerned, the authorities create a climate of fear or do nothing that can be reasonably expected of them to assure those comtemplating flight that they would be protected.
The government of Sri Lanka, in 1990, claimed that the militant group Liberation Tigers of Tamil Eelam (LTTE) had forcibly expelled, all at once, nearly 40,000 members of the Muslim community from the Mannar area in the northern part of the country, which had led to a massive number of displaced and missing persons.