Immigration detention in the United Kingdom is the practice of detaining foreign nationals for the purpose of immigration control. Unlike other countries within the European Union, UK provisions to detain are not outlined in a codified constitution. Instead, immigration enforcement holds individuals under Powers granted in the Immigration Act 1971 and by the Home Office Detention Centre Rules (2001). The expressed purpose of immigration detention is to "effect removal; initially to establish a person's identity or basis of claim; or [implement] where there is reason to believe that the person will fail to comply with any conditions attached to a grant of immigration bail." Detention can only lawfully be exercised under these provisions where there is a "realistic prospect of removal within