3.The principal purpose of the Order is to provide the Northern Ireland Prison Service with enabling powers for mandatory drug and alcohol testing of prisoners as part of its comprehensive strategy aimed at reducing drugs misuse in prisons. The Order also contains a declaratory provision in relation to the temporary detention of persons - committed to prison by the Courts - in police custody in circumstances where admittance to prison is impracticable and deals with certain other miscellaneous matters, detailed below, which require the amendment or repeal of existing provisions in the Prison Act (Northern Ireland) 1953.