Insanity and Automatism

We published a discussion paper on 23 July 2013 with our provisional proposals for reform of the defences of insanity and automatism, based on lack of capacity.

Work in this area is paused for the moment.

When should a person not be criminally liable because of their mental condition at the time they committed an alleged offence?  This is the question posed by what is called the defence of “insanity”.

Similarly, a person might not be criminally liable because they lacked conscious control of their actions at the time of committing the alleged offence for a reason other than their mental condition.  This might amount to a defence of “sane automatism” under the current law.

The current rules that govern the insanity defence (also referred to as “insane automatism”) date from 1843.  They have been widely criticised for a number of reasons:

  • it is not clear whether the defence of insanity is even available in all cases;
  • the law lags behind psychiatric understanding, and this partly explains why, in practice, the defence is underused and medical professionals do not apply the correct legal test;
  • the label of “insane” is outdated as a description of those with mental illness, and simply wrong as regards those who have learning disabilities or learning difficulties, or those with epilepsy;
  • the case law on insane and non-insane automatism is incoherent and produces results that run counter to common-sense.

The empirical data suggest that there are only a very small number of successful insanity pleas each year (typically under 30).  We published a scoping paper in July 2012 in which we asked questions to discover whether the current law causes problems in practice, and if so, the extent of those problems.  The responses to that paper have informed the Discussion Paper.

In the Discussion Paper we set out provisional proposals for reform of the defences of insanity and automatism, based on lack of capacity.  We explain how they would work with the law on intoxication.  We also say why we think the related issue of children’s developmental immaturity merits separate investigation.

Work in this area is paused for the moment. Although we have no immediate plans to restart, we remain committed to conducting the final stages of the project – consulting on provisional proposals and making recommendations to Government – when we can.

We have a linked project on the related problem of unfitness to plead.

Documents and downloads

Project details

Area of law

Criminal law


Professor David Ormerod QC