The criteria take their name from a single nineteenth-century case, but the test as applied today is the product of nearly two centuries of refinement.
R v Pritchard (1836)
In R v Pritchard (1836) 7 C & P 303, the defendant — who was deaf and unable to speak — faced a capital charge. Trying the question of whether he could be tried at all, Baron Alderson directed the jury to consider three things: whether the defendant was mute by malice or by the act of God; whether he could plead to the indictment; and, critically, whether he was of sufficient intellect to comprehend the course of the proceedings so as to make a proper defence — to know that he might challenge a juror, and to understand the evidence.
That third question is the seed of the modern test. It located fitness not in diagnosis but in ability — the practical capacity to engage with a trial.
The line of authority runs back even earlier, to cases such as R v Dyson (1831) and R v Davies (1853), but it is Pritchard that gave the test its name and its enduring shape.
R v M (John) (2003)
The language of 1836 does not map neatly onto a modern criminal trial. Over time the courts restated the test, and the authoritative modern formulation came in R v M (John) [2003] EWCA Crim 3452. There, the Court of Appeal set out the six abilities now universally referred to as the Pritchard criteria. To be fit to plead and stand trial, a defendant must be able to:
- understand the charges;
- decide whether to plead guilty or not;
- exercise the right to challenge jurors;
- instruct solicitors and counsel;
- follow the course of the proceedings; and
- give evidence in their own defence.
The crucial structural feature of the test is this: the criteria are conjunctive in effect. A defendant must be able to do all six. An inability in respect of any single one is enough to render the defendant unfit. That is why a careful assessment must address each limb in turn, rather than reaching a global impression.
In Podola [1960] 1 QB 325, Lord Parker CJ described the tests as firmly embodied in our law — and so they have remained. Despite sustained criticism (see Criticisms and the future of the test) and despite recommendations for reform, the Pritchard / M (John) criteria are the law the courts continue to apply.