This was a case in which certain prisoners had rioted and therefore had their remission of sentence reduced as punishment by the Board of Visitors (a statutory body in charge of prison punishments). The prisoners brought an action claiming that the Board had acted outside of their jurisdiction for breaching the rules of natural justice. On the facts the appeal was dismissed.
Lord Diplock: In public law the prisoners had a legitimate expectation of remission and would be entitled to an award against the Board if it could be shown to have acted beyond its jurisdiction , which includes breaching the rules of natural justice (“which means no more than to act fairly towards him in carrying out their decision-making process”). Even where the statute does not stipulate that a fair hearing must be given (though the act in question did), this is to be presumed as parliament’s intention, breaching which would render any decision a nullity.