An act cannot be punishable if it is carried out involuntarily. Criminal liability requires voluntary acts. A successful plea could result in a complete acquittal. For this reason, the courts have narrowly interpreted the defence to make it difficult for defendants to rely on it.
The defence requires the cause to be an external factor. Applying this to David’s case, it can be submitted that the alcohol David consumed satisfies this element.
David must then provide evidence that because of the alcohol, he suffered a total loss of voluntary control as outlined in the case of Broome v Perkins. When applied to the facts, it can be argued that although the alcohol had an effect on David’s reaction, there was no total loss of voluntary control because the attack would have required some level of control and this would not satisfy the defence.
It is also unlikely that the courts would equate his reaction to a reflex. There issue of self induced automatism is also raised because the law will not protect a defendant if his automatism is induced by his own actions especially if alcohol and drugs are involved. It can be argued that David induced his state of automatism because he voluntarily and knowingly consumed alcohol. Public policy would require that a person be liable for his conduct and for the above reasons, the defence fails.
David could plead insanity. Provided that the defence shows evidence of insanity and expert medical evidence of two medical practitioners is given, the jury may return a special verdict of ‘not guilty by reason of insanity’. Successful pleas result in supervision, treatment or guardianship orders and acquittals, although murder charges require indefinite detention in hospital.
The defence requires that the McNaghten Rules be