1. The concept of insanity and its possible use as a defence in the negation of criminal liability first appeared in R v Arnold. Tracy J put forward that if an offender is "totally deprived" of their "understanding and memory", then they should never be subject to punishment. The notion of criminal insanity was further developed in R v Hadfield. This case lead to The Criminal Lunatics Act 1800 being passed; to allow for the detention of insane individuals.
2. This report will concern itself, however, with the current law and it's efficacy for dealing with the 'insane'. At present, the definition of the insanity defence is found in the 'M'Naghten Rules'. To establish a defence of insanity,
"...it must be clearly proved that, at the time of the committing
of the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong."
It lies with the defendant to prove that on the balance of probabilities that they fall within the confines of the test, and are thus insane. If proven, the individual is found 'not guilty by reason of insanity' (NGRI) and is at the 'disposal' of the court, meaning they can be discharged, given a supervision order or detained within a psychiatric institution.
3. The 'M'Naghten Rules' on insanity have various shortcomings. Firstly, it is not clear whether the insanity defence available to all defendants. Secondly, the current law is, in various ways, incompatible with modern psychiatric and medical understanding. Additionally, describing a defendant as 'insane' is outdated and offensive. Lastly, the application of the M'Naghten Rules' can contravene the EU conventions following guidance created in EU cases. This report shall scrutinise current law, and ultimately suggest that the it should be reformed.
Availability of the Insanity Defence
4. Firstly, an anomaly exists in relation the employment of the insanity defence in cases heard in magistrates' courts. Certain interpretations of the judgment in DPP v Harper, the defence is not available for strict liability offences heard in the magistrates' court. However, if the same were to be tried in the Crown Court then an insanity plea would be allowed.
5. Additionally, the judgment has been deeply criticised by legal pundits. Tony Ward critiques the Harper case and the clouding effect that it had upon availability of the insanity defence. Ward states that there are various ways in which the case may be clarified. One explanation is that the judgment states that insanity cannot be a defence to a crime of strict liability.
6. Considering this, Ward asserts that if this is indeed the ratio of the case then the 'decision but be considered per incurium' owing to its disregard for the decisions of related cases such as R v Hennessy. ...