The United Nations Working Group on Arbitrary Detention (WGAD) has identified five categories of arbitrary detention:

1. When it is clearly impossible to invoke any legal basis justifying the deprivation of liberty (as when a person is kept in detention after the completion of their sentence or despite an amnesty law applicable to them);

2. When the deprivation of liberty results from the exercise of the rights or freedoms guaranteed by Articles 7, 13, 14, 18, 19, 20 and 21 of the Universal Declaration of Human Rights and, insofar as States parties are concerned, by articles 12, 18, 19, 21, 22, 25, 26 and 27 of the International Covenant on Civil and Political Rights;

3. When the total or partial non-observance of the international norms relating to the right to a fair trial, spelled out in the Universal Declaration of Human Rights and in the relevant international instruments accepted by the States concerned, is of such gravity as to give the deprivation of liberty an arbitrary character;

4. When asylum seekers, immigrants or refugees are subjected to prolonged administrative custody without the possibility of administrative or judicial review or remedy;

5. When the deprivation of liberty constitutes a violation of international law for reasons of discrimination based on birth; national, ethnic or social origin; language; religion; economic condition; political or other opinion; gender; sexual orientation; or disability or other status, and which aims towards or can result in ignoring the equality of human rights.