Excerpt from Stand Against Injustice:
“Mansfield knew that if Barry had been put into such a hospital it would be impossible for him to recover from the disabilities he was born with. The Dando case would very quickly have disappeared and Barry would have been detained indefinitely, probably never to be released again. Everyone would have believed the case had been solved and Barry would never have had a trial, fair or otherwise. (Michelle Diskin Bates)
Fitness to Plead in the Crown Court“The purpose of this procedure is to strike a fair balance between the need to protect a defendant, who has, in fact, done nothing wrong but is unfit to plead at his trial, and the need to protect the public from a defendant who has committed an injurious act which would constitute a crime if done with the requisite mens rea (R v Antoine [2001] 1 AC 340).
The procedure is set out in the Criminal Procedure (Insanity) Act 1964 as substantially amended by the Criminal Procedure (Insanity and Unfitness to Plead) Act 1991 and by sections 22, 24, 25, Schedule 2 and the provisions in respect of unfitness to plead and insanity in Schedules 10 and 11 to the Domestic Violence, Crime and Victims Act 2004 for all defendants arraigned after 31 March 2005. Transitional provisions are set out at paragraph 8 of Schedule 12 to the 2004 Act.
The procedure has two stages:
Whether the offender is under a disability i.e. whether he is "unfit" to plead (section 4 Criminal Procedure (Insanity) Act 1964) ; and if so
Whether he did the act or made the omission charged against him (section 4A Criminal Procedure (Insanity) Act 1964).
1. Whether the offender is under a disability
The question of fitness to plead may be raised before arraignment by the prosecution, defence or Judge.
In the majority of cases it is likely that the defendant will respond to medical treatment and the trial will take place within a reasonable period .The defendant may be remanded to hospital for a report on his medical condition (section 35 Mental Health Act 1983) or for treatment (section 36 Mental Health Act 1983) while he is awaiting trial. Archbold 5-891 - 5-892.
In cases of serious or enduring disorder, the issue of fitness to plead should be determined.
If there is a reasonable chance that the prosecution case will be successfully challenged, the issue of fitness to plead should not be determined before arraignment, but postponed until a time before the defence case is opened (Archbold 4-170). This may result in a conclusive verdict of acquittal and avoids the need for the issue of unfitness to be determined at all.
The issue of fitness to plead will be decided by the Judge not the jury (ss 4 (5) Criminal Procedure (Insanity) Act 1964) on the written or oral evidence of two or more registered medical practitioners, at least one of whom must be duly approved under section 12 Mental Health Act 1983.
https://www.cps.gov.uk/legal-guidance/mentally-disordered-offenders