Second, where a person is found fit to plead, the trial will proceed, but the person may raise the defence of insanity. The law will presume that the person is legally sane and, if over the age of 14 years, is fully accountable for his or her actions. However, if the person is able to show, on a balance of probabilities as opposed to proving it beyond reasonable doubt, that at the time the offence was committed, he or she was legally insane, then he or she will have a defence. In these circumstances, the person will be deemed to have lacked the necessary mens rea, or guilty mind, and should not, therefore, be held accountable. The test applied here is based on the M'Naghten rules to which I have already referred. Those rules require that it must be shown that a person must have suffered, at the time of his or her act, from a defect of reason due to disease of the mind so that he or she did not know what he or she was doing, or did not know that it was wrong.