202302559 B1 - [2025] EWCA Crim 1149

Appeals where a defendant has pleaded guilty:

In Tredget this court identified three categories of case in which a conviction may be found to be unsafe even though the defendant had pleaded guilty to it: where the guilty plea was equivocal or was otherwise vitiated; where there was a legal obstacle to the defendant’s being tried; and where it was established that the defendant did not commit the offence. In each category, it is for the defendant to establish the circumstances on which he relies.

As to the first category, the court at [158] accepted that a guilty plea may be vitiated by erroneous legal advice or a failure to advise as to a possible defence; but only if the effect of the deficient advice was to deprive the defendant of a defence which would probably have succeeded. The court cited in this regard R v Boal [1992] QB 591, in which it was held that this court may exceptionally intervene if a possible line of defence is overlooked, but only if the defence would quite probably have succeeded and the court concludes, therefore, that a clear injustice has been done.