A magistrate had committed P for trial on the basis of inadmissible evidence alone. HL held that although judicial review was discretionary, a decision based on a finding of fact, for which there was no admissible or relevant evidence, will usually be set aside. This was unlikely to arise if the evidence considered was admissible but merely insufficient.
Lord Cooke: “To convict or commit for trial without any admissible evidence of guilt is to fall into an error of law”. Since the magistrate’s court is an “inferior” court, it is subject to judicial review.