When will an extradition judge consider the credibility of a witness?

Finally, I would note that Hall J.A. in his concurring reasons in United States of America v. Graham, 2007 BCCA 345; 222 C.C.C. (3d) 1, expressed the view that it would rarely be appropriate for an extradition judge to embark on a consideration of evidence that invites assessment of the credibility of a proposed witness: … I would consider it an extremely rare situation when an extradition judge could properly enter upon a consideration of the credibility of witnesses. Credibility is pre-eminently a jury question to be left to be considered by the trier of fact. Unreliability of evidence could arise for instance from serious deficiencies in the body of circumstantial evidence or from the opportunity for a witness to know or observe factual matters. But the mere fact that the witness might be thought by an extradition judge to be of less than stellar credibility would not normally suffice as ground to refuse a committal order. That sort of issue, in my opinion, is best left to be decided by the trial court. [At para. 41.]