Insanity

Insanity

Insanity makes available the special verdict of not guilty, but insane. The principles upon which this defense is based were set out in the M’Naughten rules.

1. Defect of reason

Firstly, the defendant must prove on the balance of probabilities that she/he must be suffering from a defective reason. This may be temporary or permanent. A defective reason is more serious than mere forgetfulness (Clarke).

2. Disease of the mind

Secondly, the defective reason must be caused by the disease of a mind. This can be caused by a variety of internal factors, either mental diseases or physical ones that affect there mind. Examples would be epilepsy, hyperglycemia, and even sleepwalking.

3. Nature and quality of act

Finally, the defective reason must result in the defendant not knowing either the nature and quality of his act or that it was wrong. In Windle the defendant suffered from a form of medical insanity, but could not use the defense as there was evidence that he knew that his actions were legally wrong