In England and Wales the legal test of fitness to plead is based on the ruling of Alderson B. in R v Pritchard.
[4] In Scotland the test is based on HMA v Wilson, and has two elements: The question of unfitness to plead is determined by a judge.
[6] The decision should normally be made as soon as it arises,[7] which would ordinarily be before arraignment, but the court may postpone consideration of unfitness until any time before the opening of the defence case.
[8] Since the 1991 Criminal Procedure (Insanity and Unfitness to Plead) Act, if the judge determines that the defendant is unfit to plead, a "trial of the facts" is held in which evidence is heard and the jury asked to determine whether the defendant did the act or made the omission charged against them as the offence.
For example, in New York, if a defendant's capacity to understand the proceedings and participate in his or her defense is in question, the court will order that the defendant be examined by two independent medical professionals and conduct a hearing to consider the medical evidence, a procedure known as a "730 examination" as it is governed by Section 730 of the New York Criminal Procedure Law.