8 The circumstances in which it may or may not be appropriate to order the determination of a preliminary question have been considered in many cases. Generally speaking, the Court is reluctant to order determination of a separate question except where it is clear that its resolution is likely to be determinative of the proceedings as a whole. Other considerations relate to the economical and efficient conduct of the proceedings, and include whether the determination of the preliminary question may result in the earlier determination of the outstanding issues by reducing the remaining issues between the parties and facilitating the consensual resolution of remaining issues, whether there will be a saving of costs, and whether there will be duplication of evidence and issues if there are multiple hearings. It is plainly the case that costs can often be saved by the early determination of some questions, but as Kirby and Callinan JJ said in Tepko Pty Ltd v The Water Board (2001) 206 CLR 1 (at 55):
Single-issue trials should, in our opinion, only be embarked upon when their utility, economy, and fairness to the parties [of that course] are beyond question.
9 The principal factors, then, which bear on the exercise of the discretion whether or not to order determination of the first issue as a separate question in this case are, first, whether the separate determination of that question is likely to be determinative of the proceedings; and, secondly, whether a saving of time and costs will be achieved by that course.
10 The plaintiff is ready to proceed to a final hearing on all issues now. The defendants say that they wish to issue subpoenas, obtain authorities from the plaintiff to gain information from Centrelink, and then brief an expert. Why they have not done any of this before the matter was referred to the call-over list is unexplained and does not attract sympathetic consideration, but even assuming that the defendants are to be permitted to embark on that course, that is something which presumably can be attended to in a month or two, so that the matter would be ready for hearing at least early in the New Year on a final basis.
11 If a determination of separate question is ordered, it is unlikely to be heard before the New Year, given the current state of the lists. In those circumstances, even if there is not an application for leave to appeal, the final hearing of the matter, if the plaintiff succeeds on the first issue, is unlikely to take place much before the end of 2007. There is at least a possibility that this would be further delayed by an application for leave to appeal. While I accept that one does not look at the history between two firms of solicitors which have litigated this type of case in the past and deduce from that that there will inevitably be an application for leave to appeal, nonetheless the prospect cannot be overlooked. I sought, but was not proffered, an undertaking from the defendants that, without prejudice to their rights to appeal on a final basis, they would not seek leave to appeal on an interlocutory basis from determination of the separate question.
12 On the second issue, the plaintiff proposes to rely only on the medical evidence that was before the trustee when the trustee made its decision. That is evidence which will be tendered on the first issue in any event. There will therefore be a substantial overlap of relevant evidence. The significant difference seems to be that on the second issue there will be cross-examination of some or all of medical experts, and possibly a further expert to be called by the defendant. However, a proper appreciation of that cross-examination and any further expert evidence will require an understanding of the evidence adduced before the trustee, and therefore on the first issue.
13 If the first issue is resolved in favour of the defendants, it will be determinative of the proceedings, but if it is resolved in favour of the plaintiff, it will not. In that sense, as the plaintiff submits, ordering a separate question is almost entirely for the benefit of the defendants. It is not absolutely entirely so, because the plaintiff's costs of the second question, if he fails on the first, might be saved; but if the plaintiff is to succeed, then there is no benefit to him in the determination of the first issue as a separate question. If he succeeds on the first issue, the plaintiff will effectively have to prepare for, and fund, not one, but two trials. This is not fairness to both parties, in the sense in which Kirby and Callinan JJ spoke in Tepko.