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Prevalence of mental disorder in defendants at criminal court

Research output: Contribution to journalArticlepeer-review

Original languageEnglish
JournalBJPsych Open
Accepted/In press25 Apr 2022

King's Authors


Background: Psychiatric morbidity in prisons and police custody is well-established, but little is known about individuals attending criminal court. There is international concern that vulnerable defendants are not identified, undermining their right to a fair trial.
Aims: To explore the prevalence of a wide range of mental disorders in criminal defendants and to estimate the proportion likely to be unfit to plead.
Methods: We employed two-stage screening methodology to estimate the prevalence of mental illness, neurodevelopmental disorders and unfitness to plead in 3322 criminal defendants in South London. Sampling was stratified according to whether defendants attended court from the community or custody. Face-to-face interviews using diagnostic instruments and assessments of fitness to plead were administered (n=503). Post-stratification probability weighting provided estimates of the overall prevalence of mental disorder and unfitness to plead.
Results: Mental disorder was more common in those attending court from custody, with 48.5% found to have at least one psychiatric diagnosis compared to 20.3% from the community. Suicidality was frequently reported (weighted prevalence 71.2% (95% CI 64.2-77.3). Only 16.7% of participants from custody and 4.6% from the community were referred to the liaison and diversion team. 2.1% (1.1-4.0) of defendants were estimated to be unfit to plead, with a further 3.2% (1.9-5.3) deemed “borderline unfit”.
Conclusion: The prevalence of mental illness and neurodevelopmental disorder in defendants at court is high. Many are at risk of being unfit to plead and require additional support at court yet are not identified by existing services. Our evidence challenges policy-makers and healthcare providers to ensure that vulnerable defendants are adequately supported at court.

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