If a person has an addiction to alcohol or other drugs and is convicted of an unlawful act committed while he was intoxicated or as a result of his addiction, or is not convicted only because he has been found to be insane or insanity cannot be excluded on the evidence, the court shall make a custodial addiction treatment order if there is a danger that he will commit future serious unlawful acts as a consequence of his addiction.

Such order shall not be made unless ab initio there is a sufficiently certain prospect of success that the person can be healed by way of custodial addiction treatment or that a relapse into addictive behaviour and the commission of serious unlawful acts caused by that addiction can be prevented for a substantial period of time.