Where the event in question is one which cannot occur without default on the part of one party to the contract, the position is clear. The provision is then construed as making the contract not void but voidable: only the party who is not in default can avoid it, and he may please himself whether he does so or not. In the present case the happening of the event (not obtaining the Treasurer's consent) may be brought about by failure on the part of either party to take certain necessary steps (provision of particulars by the vendor or making of application by the purchaser) to obtain the Treasurer's consent, or it may be brought about without any default on the part of either party. In fact, although there was some argument to the contrary, it was, we think, brought about without any default on the part of either party. Such a case is perhaps not quite so clear as the simpler case where the event cannot occur without default on one side or the other. But we are of opinion that the New Zealand Shipping Case requires the same construction to be given to the contract in both classes of case. The provision in question is to be construed as making the contract not void but voidable. The question of who may avoid it depends on what happens. If one party has by his default brought about the happening of the event, the other party alone has the option of avoiding the contract. If the event has happened without default on either side, then either party may avoid the contract. But neither need do so, and, if one party having a right to avoid it does not clearly exercise that right the other party may enforce the contract against him. This is, we think, the view of Lord Shaw and Lord Wrenbury in the New Zealand Shipping Case, and it is consistent with what was said by Lord Finlay L.C. The language of Lord Atkinson may perhaps be regarded as expressing a different view, but we doubt whether his Lordship had in mind the precise point which arises here and which did not arise in the New Zealand Shipping Case. Although the effect of a provision in a contract may differ according to the events which happen, its construction cannot differ according to the events which happen. If "void" means "voidable," it means "voidable" whatever happens. It cannot very well mean "voidable" if an event happens through the default of one party, and "void" if the event happens without default by either party.
44 That passage could be read as setting out a principle of law rather than a mere guide to construction, but to so read it would in my opinion be against very well-established principles concerning the construction of contracts, including the principle that, if words used in a contract are unambiguous, the Court must give effect to them: Australian Broadcasting Commission v. Australasian Performing Rights Association (1973) 129 CLR 99 at 109. The passages referred to earlier in Sandra Investments are to similar effect. Accordingly, I respectfully agree with what Samuels JA (with the concurrence of Priestly JA and McHugh JA) said in Rudi's Enterprises, particularly in the following passage at 579:
I cannot think that the Court in Suttor intended to lay down the proposition that parties could not stipulate for automatic termination of a contract save upon the occurrence of an event which, objectively, lay beyond their control. Effect must be conceded to the parties' intention.
45 Thus, as asserted in Rudi's Enterprises, where the parties have clearly stipulated for automatic termination upon the occurrence of an event which could occur either without the default of either party or with the default of one or other party, and if the event occurs through the default of one party, then, although in general terms this would mean automatic termination, the party whose default caused the event can be prevented from taking advantage of this by direct application of the principle that a party cannot take advantage of its own wrong, rather than through construing the contract contrary to its clear meaning.
46 I appreciate that, in some circumstances, this could give rise to uncertainty. If one has such a contract and the invalidating event occurs through the default of one party, that party will be in doubt as to whether performance of the contract is or is not required of it, unless some notice is given by the party not in default. However, I do not think this consideration does more than generally support the Suttor approach to construction.
47 In my opinion, the Suttor principle of construction applies most powerfully if the invalidating event can occur only through a breach of contract by one or other party. The lesser the likelihood that the disabling event occur through the breach of one or other party, as distinct from some cause outside the control of the parties, the less powerfully does the principle apply. In the case of cl.2A of the Development Contract, it appears that there are many matters outside the control of the parties that could cause the non-fulfilment of the conditions precedent. So in my opinion, the Suttor principle does not apply at full strength. In my opinion, the wording of cl.2A(b), and particularly the use of the word "automatically", clearly shows that the parties' intention, as manifested by the words they chose, was that the contract would be automatically rescinded and that no notice was required; and that intention should prevail in the construction of the contract.
48 However, I would add that this conclusion is subject to the effect of the respondents' argument based on conventional estoppel, raised by their Notice of Contention; and for that reason I will address questions that arise only if the contract was not automatically rescinded.