What is a judge’s duty to deal with "likely to give material evidence"?

In Foley v. Gares, Bayda C.J.S. made the following remarks regarding a judge’s duty to deal with “likely to give material evidence”, at 88: What type of inquiry is a justice acting under ss. 626 and 627(2)(a) required to make? It is safe to say that the standard of inquiry is not so high, for example, as that expected of a judge acting under s. 627(3), but the justice nonetheless should make some examination of the circumstances. He is given discretion in the matter of issuing the subpoena and he should exercise it judiciously if not judicially. The justice may choose not to insist upon evidence on oath but he may want to conduct an oral examination, if only a cursory one, of some person who has knowledge of the circumstances. The extent of such an examination will depend on the circumstances of each situation. One thing however is certain. If he takes no steps whatever to satisfy himself that the person is likely to give material evidence, the justice is abusing his power and his discretion if he issues the subpoena. His decision to issue the subpoena may be set aside by a superior court on the ground that without making any examination the justice had no jurisdiction to exercise his discretion to issue the subpoena. In short his decision is amenable to certiorari.