Insanity defence and mental state reports
Our psychiatrists report on your client’s mental state at the time of the offence, including insanity.
- Section 12-approved psychiatrists
- Same-day quotes and CVs
- Legal aid accepted
- Prison, video or in-person assessment
GMC-registered psychiatrists · Reports written to Criminal Procedure Rules Part 19
Mental state at the time of the offence
A defendant is insane in law if, at the time, a defect of reason from a disease of the mind meant they did not know the nature and quality of the act, or did not know it was wrong (M’Naghten’s Case (1843)).
Whether a condition is a disease of the mind is a question of law, not medical usage (R v Coley [2013] EWCA Crim 223). Our psychiatrists give the clinical evidence on each limb; the court decides whether the legal test is met.
Questions our psychiatrists answer
- Your client’s mental state at the time of the offence, reconstructed from the records and witness evidence
- Diagnosis, including psychosis, mood disorder and organic conditions
- Whether your client knew the nature and quality of the act, and knew it was wrong
- Clinical evidence relevant to intent, where the charge requires it
- The part played by alcohol or drugs, and whether any psychosis was self-induced
- Whether symptoms could be feigned or exaggerated
- Fitness to plead, where it is also in question (see fitness to plead assessments)
Intoxication
A mental malfunction caused by an external factor, such as drink or drugs taken voluntarily, is not a disease of the mind (Coley). The expert separates the effects of intoxication from any underlying illness.
Automatism
Where automatism is raised, the expert addresses whether there was a complete loss of voluntary control and whether its cause was internal or external, since an internal cause leads to the insanity verdict.
After the special verdict
A verdict of not guilty by reason of insanity leads to a hospital order, a supervision order or an absolute discharge (1964 Act, section 5). The expert can report on the right disposal.
Current position checked 10 November 2026
The Law Commission’s work on insanity and automatism stopped at a 2013 discussion paper and has not led to a report or a bill. The M’Naghten Rules and the 1991 Act apply as they stand.
Written for the court
Every report is written to the requirements of Criminal Procedure Rules Part 19 and the Criminal Practice Directions in force when it is signed.
Two medical opinions
The special verdict needs evidence from two doctors, one approved under section 12 (1991 Act, section 1). Tell us if you need both.
Records first
The expert reconstructs the mental state from contemporaneous records and witness accounts, not your client’s account alone.
Feigning considered
The report considers whether symptoms could be feigned or exaggerated, which strengthens the opinion when it is tested.
Duty to the court
The expert’s duty is to the court, and it overrides any obligation to the solicitor who instructs or pays them.
A psychiatrist for your mental state defence
Send us the case details and we will come back with expert CVs and an itemised quotation.
Common questions
Is insanity a complete defence?
Yes. A successful defence leads to the special verdict of not guilty by reason of insanity, followed by a hospital order, a supervision order or an absolute discharge.
How many medical opinions does the special verdict need?
Two. The jury can return it only on the written or oral evidence of two or more registered medical practitioners, at least one approved under section 12 of the Mental Health Act 1983.
Can drug-induced psychosis support an insanity defence?
Not where the psychosis was caused by drink or drugs taken voluntarily, which is an external cause (R v Coley). An underlying illness is a different question, and the expert addresses it.
What about the magistrates’ court?
The special verdict does not apply there, but the court can make a hospital order without convicting under section 37(3) of the Mental Health Act 1983.
Do you accept legal aid?
Yes. We routinely support legally aided matters and provide itemised quotations and expert CVs for prior authority applications to the Legal Aid Agency.
How long does a report take?
Standard turnaround is 10 to 15 working days after assessment and receipt of records. Urgent and fast-track options (24 to 72 hours) may be available depending on complexity and diary capacity.
Other criminal reports
Diminished responsibility
Section 2 evidence in murder cases, including loss of control.
Hospital and hybrid orders
Sections 37, 41, 38 and 45A, remand to hospital and transfers from prison.
Fitness to plead
Pritchard criteria, trial of the facts and effective participation.
Parole Board reports
Independent risk reports for parole reviews, recalls and progression.
Risk assessments
Violence, sexual and fire-setting risk for sentence and disposal.
Sentencing and mitigation
Culpability, mitigation and community orders with treatment.
Modern slavery defence
Section 45 evidence on trauma, vulnerability and relevant characteristics.
Vulnerable defendants
Interviews, confessions, intermediaries and effective participation.
Further reading
Instruct a psychiatrist on mental state
Send us the case details and we will come back with expert CVs and an itemised quotation.