http://www.asylumpolicy.info/double.doc
"It is supposed to be a fundamental principle of the criminal law that a person cannot be punished twice for the same offence. However this does not apply to black people. This is because many black people found guilty of a crime are at risk of deportation in addition to any other sentence. Apart from certain Commonwealth and Irish citizens the only people immune from expulsion are British Citizens. However since the 1981 Nationality Act it has become increasingly hard to acquire such citizenship.Deportation of criminal offenders can take place in two ways. Firstly, it can be recommended by a court following conviction. Secondly, even where the court makes no recommendation, the Home Office can subsequently intervene and serve a deportation notice on the grounds that the prisoner's presence in the UK is not 'conducive to the public good' ."
