"There is the offence of possession of such a drug and that offence was committed by [Escott in that case, the deceased]. We have considered therefore whether that renders the act of injection unlawful for these purposes but we find it difficult to see it can do so. The causative act, the act of causing death was essentially the injection of the heroin rather than the possession of it. Self injection undoubtedly requires unlawful possession in a case such as this, but it is not in itself a separate offence. No one could be charged with injecting himself with heroin, only the possession of it. The deceased was in possession of the heroin before he injected it and also after he had injected it. Such possession amounted to an offence but the act of injecting was not itself part of the offence, it was merely made possible by the unlawful possession of the heroin."