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Fitness to plead

Scales of justice

About Fitness to plead

 “Fitness to Plead” is a fundamental but understudied concept of criminal justice. It refers to a defendant’s ability to understand and participate in the legal process, a prerequisite to a fair trial. There is a need to balance the individual’s right to make autonomous decisions regarding their trial with their ability to effectively participate. The assessment of fitness to plead is carried out by psychiatrists and determined by a judge, and the costs of dealing with unfit individuals are high.

Fit for purpose?

The issue is raised in a small proportion of criminal cases, typically by the defendant’s solicitor, and approximately one hundred defendants are adjudicated unfit to plead in England and Wales annually. This is a startlingly low number considering the high prevalence of mental disorder and cognitive impairment in the criminal justice system, and it is likely that many are not identified. One explanation lies in the antiquated test for determining unfitness, and there is a growing consensus that this should be replaced by a broader test centred on decision-making abilities, or “mental capacity”.

Proposed reforms to the law

The Law Commission recently acknowledged problems in the current law, and we have contributed to the 2010 Consultation Paper and 2016 Report “Unfitness to Plead” in which a number of reforms were proposed. These include replacing the existing criteria with a new legal test akin to the civil test for mental capacity, introducing a structured clinical instrument to assess unfitness to plead and screening for unfitness. This would improve fairness in the legal system for vulnerable defendants but is likely to lead to an increase in the number found unfit, placing considerable burden on psychiatric and legal services. 

Our Study

This project aims to refine our understanding of fitness to plead and address the implications of the Law Commission’s proposals. It aims to determine what the prevalence of unfitness to plead in defendants facing criminal trials would be if those proposals are adopted; the underlying psychiatric and sociodemographic factors that impact on unfitness; and how unfitness should be reliably identified and assessed. 

Development of a Structured Assessment Instrument

Following a grant from the Nuffield Foundation  we have developed a structured instrument for assessing fitness to plead to be used in research and clinical settings

Fitness to Plead: A Conceptual and Empirical Study

 The main part of the study is funded by a Wellcome Trust Ethics and Society Fellowship.

  • Conceptual analysis of Fitness to Plead.
Ethical analysis will be carried out in collaboration with the Essex Autonomy Project to explore how fitness to plead should be conceptualized, focusing on the roles of autonomy and decisional capacity.
  • Quantitative study: the prevalence of mental disorder and unfitness to plead at Magistrates.

We have finished recruiting 500 defendants facing criminal charges at Magistrates’ Court to estimate the prevalence of mental disorder and unfitness to plead in criminal defendants. We will also explore the clinical and demographic factors associated with an increased in risk in being unfit to plead in this group.

  • Qualitative study: where should the threshold for unfitness to plead be set?

We are in the process of recruiting a range of professionals (legal, clinical, academic) to form a focus group to further explore the concept of fitness to plead.

Interested in participating

If you are interested in participating in the focus groups or would like to know more about the study, please email

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