The approach to be taken, already identified in para 13, supra, will constitute the basis for the directions to be given to the jury. It would not be appropriate for the trial judge to direct the jury that, depending on the view they have formed of certain factual matters, the Australian Tax Office did lose something of value - or even that the rulings did put the revenue of the Commonwealth at risk. Such a direction may well be subject to various permutations and combinations of the factual matters, and the direction could lead to confusion. The more usual form of directions to a jury - and the infinitely safer one - is to define the issue which the jury must determine, then explain to them the arguments of both parties in relation to the relevant factual material, and finally conclude that, if the Crown has satisfied them that it has established that particular issue, they may move on to the next issue."
9 With respect to the nature of admissible evidence on the arguable case issue, their Honours observed at 670-671 [27]:
"Related to this issue as to whether the decision is one for the judge or the jury is the admissibility of evidence upon which the decision is to be based. In our opinion, but subject to the Crown being permitted to enlarge its particulars in the light of the decision now given by the Court of Criminal Appeal, there is no bar to the admission of relevant statements by courts or others as to the interpretation of these provisions merely because they may have come into existence after the time when the private rulings were made. What the law was at that time is an objective matter which the Crown must prove. That objective fact has nothing to do with any state of mind on the part of the accused which may be relevant to his mens rea. There is therefore no need to restrict the admissible material to material which was in existence at that relevant time. The issue as to what the law was at the relevant time may be proved by reference to what has since been held to be the law, provided that there has been no change in the relevant statutory provisions in the meantime. It is presumed to have been the law all along."
10 In a separate judgment, Mason P dissented upon the question whether the arguable case issue was one for the trial Judge or the jury. Mason P held that the arguable case issue was a matter of law, as part of a mixed question of fact and law, which the trial Judge ought determine: R v Petroulias at 691-693 [125]-[134].
11 A number of the Federal Court decisions referred to at paragraph 4 above were adverted to by Mason P in R v Petroulias at 679 [61]-[62], 691 [125], 693 [137] and 694-697 [140]-[149].