The Pritchard criteria are the law, but they are not beyond criticism. Few legal tests in regular use are as widely criticised by the professionals who apply them, and understanding those criticisms is part of understanding the test.
The principal criticisms
The test is too cognitive. The criteria focus heavily on intellectual understanding – whether the defendant can comprehend, follow and communicate. They map poorly onto conditions whose effect is not primarily cognitive: mental illnesses that distort motivation, insight or volition without impairing raw comprehension. A defendant can satisfy every limb on a literal reading and still be, in any meaningful sense, unable to participate.
It neglects decision-making capacity. Modern clinical and legal thinking, reflected in the Mental Capacity Act 2005, frames participation in terms of the ability to understand, retain, weigh and use information and to communicate a decision. The Pritchard criteria predate this framework entirely and do not expressly incorporate it, producing a mismatch between how fitness is assessed in the criminal courts and how capacity is assessed everywhere else.
It sits awkwardly with effective participation. The right to a fair trial under Article 6 of the European Convention on Human Rights requires a defendant to be able to participate effectively in their trial – a broader and more functional standard than the Pritchard limbs. The two coexist uneasily, and the gap between them is where much of the difficulty in this area arises.
It is applied inconsistently. Because the test has been repeatedly restated and is not well understood, it is applied unevenly by clinicians and courts alike. Only around 100 defendants a year are formally found unfit – roughly 0.1 per cent of Crown Court defendants – yet a study of defendants at two South London magistrates’ courts, assessed by forensic psychiatrists using a standardised fitness instrument, estimated that 2.1 per cent were likely to be unfit to plead, with a further 3.2 per cent borderline (Brown and others, BJPsych Open 2022; 8: e92). Most were never referred to the court liaison and diversion service. The authors acknowledge that the findings may not generalise beyond South London, but the gap suggests that many defendants who may be unable to participate are never identified, let alone assessed. The same study argues that the Law Commission’s estimate of how many more defendants would be found unfit under its proposed test is likely to be a substantial underestimate. There is also no clean annual statistic: published prosecution figures group unfitness with warrants, deaths and other administrative outcomes, so they cannot be read as the number found unfit.
The courts have acknowledged these criticisms – in R v Diamond [2008] EWCA Crim 923 and R v Murray [2008] EWCA Crim 1792, among others – while confirming that the criteria remain the law to be applied. See The case law.
What reform might look like
In 2016 the Law Commission recommended replacing the Pritchard criteria with a modern test built around the defendant’s decision-making capacity and their ability to participate effectively in the trial, bringing the criminal test into line with contemporary clinical understanding and with the effective-participation standard. It also proposed changes to unfitness procedure across the Crown Court, magistrates’ court and youth court. Those recommendations have not been enacted.
The practical implication is twofold. First, reform is anticipated but not here: the Pritchard and M (John) criteria remain the law, and remain what experts must assess against. Second, commentators have suggested that a capacity-based test would be likely to lower the threshold, so that more defendants would be found unfit than at present. The direction of travel is clear; the timing is not.
The Mental Health Act 2025
Separately, the Mental Health Act 2025 received Royal Assent in December 2025 and will substantially amend the Mental Health Act 1983. Most of its provisions are not yet in force and full implementation is expected to take several years, so the 1983 Act continues to govern detention, treatment and hospital disposals – including those available after a finding of unfitness – in the meantime.
The current procedure, including the position in the magistrates’ court, is set out on the Fitness to plead page. This page is updated as the position develops.