The relevant principles of law are stated in The Queen v Apostilides.[9] In that case the High Court first summarised relevant authority and then set out the principles governing the role and responsibility of a prosecutor and the powers of a trial judge. In so doing, they quoted with approval, the following passages from Richardson v The Queen:[10]
'Any discussion of the role of the Crown prosecutor in presenting the Crown case must begin with the fundamental proposition that it is for him to determine what witnesses will be called for the prosecution. He has the responsibility of ensuring that the Crown case is properly presented and in the course of discharging that responsibility it is for him to decide what evidence, in particular what oral testimony, will be adduced. He also has the responsibility of ensuring that the Crown case is presented with fairness to the accused in making his decision as to the witnesses who will be called. He may be required in a particular case to take into account many factors, for example, whether the evidence of a particular witness is essential to the unfolding of the Crown case; whether the evidence is credible and truthful and whether, in the interests of justice, it should be subject to cross-examination by the Crown, to mention but a few.
What is important is that it is for the prosecutor to decide in the particular case what are the relevant factors and in the light of those factors to determine the course which will ensure the proper presentation of the Crown case, conformably with the dictates of fairness to the accused. It is in this sense that it has been said that the prosecutor has a discretion as to what witnesses will be called for the prosecution but to say this is not to give the prosecutor's decision the same character as the exercise of a judicial discretion, or the exercise of a discretionary power, or to make his decision reviewable in the same manner as those discretions are reviewable. In the context the word discretion signifies no more than that the prosecutor is called upon to make a personal judgment, bearing in mind the responsibilities which we have already mentioned.'
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There may be circumstances where fairness to the accused requires a prosecutor or the court to call a witness who is able to give evidence which the jury may regard as highly significant, despite doubts as to the truthfulness and reliability of that witness. Nevertheless in my view, [the prosecutor in this case] is entitled to form his own opinion as to whether the admitted unreliability and apparent partiality of the accused's brother, has rendered him unsatisfactory as a witness for the Crown, because he will be neither credible nor truthful nor demonstrative of the underlying truth.
By this last consideration I mean [the prosecutor] is entitled to consider whether any proper inferences could be drawn from untruthful answers in the circumstances of the case as a whole. The prosecutor is further entitled to form a view as to whether, if Colin is called to give evidence, it is in the interests of justice that the Crown cross-examines him.[11]
Having regard to the situation as I have analysed it, it does not appear to me to be one of most exceptional circumstances.
In closing submission, [defence counsel] sought in the final further alternative, leave to call and cross-examine Colin as part of the defence case. In my view, such an application should not be determined until the conclusion of the Crown case. Insofar as necessary however, I specifically reserve leave to [defence counsel] to re-agitate the issue of evidence from Colin at the conclusion of the Crown case in any manner he sees fit.[12]