Preventive detention laws authorize courts to order the continued detention in prison of a person who has served their allocated term of imprisonment, but who are thought to be at risk of re-offending if released. They raise fundamental issues about the separation of powers, the purpose of incarceration, and the standard of proof which is/should be required to authorize detention. They assume that it is possible to predict, with a satisfactory rate
of success, whether or not a past offender would if released commit further offences. Recently, a majority of the High Court of Australia validated such legislation. The author in this article explains his reasons for disagreeing
with the verdict of the Court in this matter
