Removal, detention and bail
A person may be subject to being removed from the UK if they have no leave to remain or enter the UK or they are an illegal entrant. The Secretary of State has been given a statutory power to detain those who are subject to immigration control. If a person is detained in circumstances where there is not a statutory power to detain, the detention is unlawful. It is rare for a person to be detained unlawfully at the outset. However, it is possible that the detention becomes unlawful because of changes of circumstances or simply because of the passage of time.
The Secretary of State is also under a continual obligation to seek an alternative to detention. All reasonable alternatives to detention must be considered before detention is authorised. Once detention has been authorised, it must be kept under close review to ensure that it continues to be justified.
Bail can be an alternative to detention. Most immigration detainees have a right to apply for bail to the Home Office or to the Asylum and Immigration Tribunal.