- The defendant must have disease of the mind.
- The defendant must have defect of reason.
- The defendant did not know the nature and quality of the act he was committing. OR
- The defendant did not know that his actions were legally wrong.
The first rule is that the defendant must have ‘disease of mind’ but here we are not talking about the medical definition. The cause of the disease of mind must be internal meaning that the likes of brain tumours don’t count. The internal part of the rule means that there should be a malfunctioning of the mind where the term ‘mind’ includes the mental faculties of reason, memory and understanding. If for example someone has diabetes and suffers a hyperglycaemic attack such as in the case of Hennessy 1989, where the defendant didn’t take his insulin and had a hyperglycaemic episode and then took a car and drove it whilst being disqualified. It was proven that because the defendant had disease of the mind, defect of reason, not knowing the nature and quality of the act and not knowing it was wrong he was therefore able to have a successful claim of insanity.
However one case where disease of mind was dismissed due to external reasons was in Rabey 1978 the defendant was dumped by his girlfriend in the geology lab and so he picked up a rock and high the girl over the head and killed her. He had no internal factors which could support his claim for insanity which meant his verdict was guilty. This was also the case in T 1990 as the defendant committed a robbery and wounding after being raped as she suffered from post-traumatic stress disorder, she was found guilty as post-traumatic stress disorder is an external constraint and therefore no claim of insanity however it was acknowledged that this was a bad decision on the Crown Courts behalf as she had been raped.
A ‘defect of reason’ is where the defendant must show that he or she was suffering from a defect of reason and that his or her ability to reason was impaired and this could be permanent or temporary. However there are clear stipulations that things like confusion or lack of concentration cannot count, therefore meaning that a defendant who still possessed those powers but failed to use them cannot be classed as insane. For example Clarke 1972 was a depressed shoplifter who pleased a lack of mens rea due to confusion and absentmindedness resulting from depression. She pleaded not guilty when the judge confronted her about her state of mind at the time however she was finally found guilty as absentmindedness cannot count as a defect of reason as she was still able to reason with the situation but decided against it.
In Kemp 1956 there was a successful plea of insanity as the defendant had arteriosclerosis and he lost consciousness presumably whilst doing DIY and hit his wife with the hammer. To many peoples surprise the wife had him charged with s.20 GBH even though he was unconscious and may not have meant to do it. It was confirmed that he had a disease of mind, defect of reason, not knew the nature and quality of the act and whether it was wrong as he was unconscious and therefore was found not guilty.
‘Not knowing the nature and quality of the act’ is where the defendant needs to have thought that he was doing something totally different, or be having some kind of fit such as an epileptic fit. For example if a defendant thinks that they were putting logs of wood on the fire but in fact but a new born baby on the fire then they would have a successful claim that they did not know the nature and quality of the act. So it is where the defendant thought they were doing something other than what they actually did and could not comprehend the morality of what they were doing.
In Burgess 1991 the defendant attacked a girl with a bottle and a video recorder and grabbed her throat although he claimed he was sleepwalking. It was proved that he didn’t know the nature and quality of his act as he was in a state where he did not know what he was doing. In Bell 1984 the defendant used his car as a battering ram to try and drive into a holiday camp, he claimed that he was ordered to do it by God and was found guilty of reckless driving because although he had a defect of reason he knew exactly what he was doing at the time (the nature and quality of the act).
The final rule is that the defendant must be able to prove that he did not know that what he was doing was wrong in the eyes of the law. In simpler terms it just means that he did not know that he was committing a crime. One case where the defendant tried to claim insanity but did not have a successful appeal was in Windle 1952 as the defendant killed his wife by giving her over 100 aspirin tablets, there was a suggestion that he had some kind of mental illness, but when he was talking to the police he said “I suppose they will hang me for this” which shows that he knew what he did was wrong and that there would be consequences for his actions. He was therefore found guilty of murder.
Another case was Sullivan 1984 where the defendant suffered from epilepsy and was charged with s.47 ABH caused whilst having a fit at his friend’s house, he attacked his friend whilst in the course of the fit which later passed. He was found guilty only due to the fact that he pleaded guilty and didn’t want to go to a mental hospital and would prefer to go to prison. He was proved to have not known what he was doing was wrong as during an epileptic fit all your understanding and reasoning goes out of the window and you don’t know what you are doing and whether it is right or wrong.