Legal principles
27 The principles governing whether parties have entered into a binding and enforceable agreement, where terms have been agreed and those agreed terms will be dealt with in subsequent formal documentation, are well settled.
28 The High Court in Masters v Cameron (1954) 91 CLR 353 at 360 (Dixon CJ, McTiernan and Kitto JJ) identified the following categories of cases in which parties have agreed on terms, but also agreed that those terms will be dealt with by subsequent formal documentation:
(a) a case in which the parties have reached finality in arranging all the terms of their bargain and intend to be immediately bound to the performance of those terms, but at the same time propose to have the terms restated in a form which will be fuller or more precise but not different in effect;
(b) a case in which the parties have completely agreed upon all the terms of their bargain and intend no departure from or addition to that which their agreed terms express or imply, but nevertheless have made performance of one or more of the terms conditional upon the execution of a formal document; and
(c) a case in which the intention of the parties is not to make a concluded bargain at all, unless and until they execute a formal contract.
29 In the first two categories there is a binding contract, but in the third there is not: Masters v Cameron at 360-1.
30 In Baulkham Hills Private Hospital Pty Ltd v G R Securities Pty Ltd (1986) 4 NSWLR 622, McLelland J made the following observation at 628:
There is in reality a fourth class of case additional to the three mentioned in Masters v Cameron, as recognised by Knox CJ, Rich J and Dixon J, in Sinclair, Scott & Co v Naughton (1929) 43 CLR 310 at 317, namely, "…one in which the parties were content to be bound immediately and exclusively by the terms which they had agreed upon whilst expecting to make a further contract in substitution for the first contract, containing, by consent, additional terms".
31 The Masters v Cameron classifications are no longer, if there ever were, applied as strict categories into which such cases must fall: Pavlovic v Universal Music Australia Pty Ltd (2015) 90 NSWLR 605 (Pavlovic) at [69] (Beazley P), citing Ermogenous v Greek Orthodox Community of SA Inc [2002] HCA 8; (2002) 209 CLR 95 at 105.
32 Rather, as McHugh JA stated in G R Securities Pty Ltd v Baulkham Hills Private Hospital Pty Ltd (1986) 40 NSWLR 631 at 634:
… the decisive issue is always the intention of the parties which must be objectively ascertained from the terms of the document when read in the light of the surrounding circumstances: Godecke v Kirwan (1973) 129 CLR 629 at 638; Air Great Lakes Pty Ltd v K S Easter (Holdings) Pty Ltd (1985) 2 NSWLR 309 ay 332-334, 337.
33 The relevant principles were recently summarised by Sackville AJA (with whom Macfarlan and Gleeson JJA agreed) in Mushroom Composters Pty Ltd v IS & DE Robertson Pty Ltd [2015] NSWCA 1 (Mushroom Composters) at [59]-[63]:
59 First, in Australia the "objective" theory of contract has been accepted: see, most recently, Electricity Generation Corporation v Woodside Energy Ltd [2014] HCA 7; 251 CLR 640 at [35]. Consequently, in determining whether a binding contract has been concluded, the law is concerned not with the parties' subjective intentions, but with "the outward manifestations of these intentions": Taylor v Johnson [1983] HCA 5; 151 CLR 422 at 428 (Mason ACJ, Murphy and Deane JJ). Thus what matters is what each party by words and conduct would have led a reasonable person in the position of the other party to believe: Pacific Carriers Ltd v BNP Paribas [2004] HCA 35; 218 CLR 451 at [22] (per curiam); Toll (FGCT) Pty Limited v Alphapharm Pty Limited [2004] HCA 52; 219 CLR 165 at [40]-[41] (per curiam). In a case where the ordinary process of offer and acceptance has taken place, the court inquires as to what a reasonable person would infer or deduce from observing the exchanges between the parties: NC Seddon, RA Bigwood and MP Ellinghaus, Cheshire & Fifoot Law of Contract (10th Aust ed 2012, LexisNexis Butterworths) at [3.4].
60 Secondly, it is not necessary, in determining whether a contract has been formed, to identify a precise offer or acceptance; nor is it necessary to identify a precise time at which an offer or acceptance can be identified: Ormwave Pty Limited v Smith [2007] NSWCA 210 at [68] and authorities cited at [68]-[75] (Beazley JA, Santow and Ipp JJA agreeing). The questions to be asked are:
"in all the circumstances can an agreement be inferred? Has mutual assent been manifested? What would a reasonable person in the position of the [plaintiff] and a reasonable person in the position of the defendant think as to whether there was a concluded bargain?"
Brambles Holdings Ltd v Bathurst City Council [2001] NSWCA 61; 53 NSWLR 153 at [81] (Heydon JA).
61 Thirdly, an agreement that is incomplete will not give rise to an enforceable contract. As was said in Booker Industries Pty Ltd v Wilson Parking (Qld) Pty Ltd [1982] HCA 53; 149 CLR 600 at 604 (Gibbs CJ, Murphy and Wilson JJ):
"It is established by authority, both ancient and modern, that the courts will not lend their aid to the enforcement of an incomplete agreement, being no more than an agreement of the parties to agree at some time in the future."
62 An alleged contract will fail for incompleteness if, even though the parties have used clear language, a term which is regarded as essential as a matter of law has not been agreed: J W Carter, Carter on Contract (2014, LexisNexis) at [04-120]. The principle was stated by Viscount Dunedin in May and Butcher Ltd v The King [1934] 2 KB 17 n at 21:
"To be a good contract there must be a concluded bargain, and a concluded contract is one which settles everything that is necessary to be settled and leaves nothing to be settled by agreement between the parties. Of course it may leave something which still has to be determined, but then that determination must be a determination which does not depend upon the agreement between the parties."
63 If the parties have not agreed on all essential terms, for example because they have left one such term to be settled by future agreement, the contract is incomplete no matter what the parties themselves may think: G. Scammell and Nephew Ltd v H.C. and J.G. Ouston [1941] AC 251 at 260 (Lord Russell of Killowen); O'Brien v Dawson [1942] HCA 8; 66 CLR 18 at 37 (Willams J, Rich J agreeing); Toyota Motor Corporation Australia Ltd v Ken Morgan Motors Pty Ltd [1994] 2 VR 106 at 170 (Tadgell J); Australian Securities and Investments Commission v Fortescue Metals Group Ltd [2011] FCAFC 19; 190 FCR 364 at [123]-[124] (Keane CJ); at [212] (Emmett J); at [223]-[227] (Finkelstein J) (an appeal to the High Court was allowed, but not on this point: Forrest v Australian Securities and Investments Commission [2012] HCA 39; 247 CLR 486).
34 The acceptance must correspond with the offer and must be clear and unqualified, and will fail to take effect if it attempts to vary the offer or add new terms: Lark v Outhwaite [1991] 2 Lloyd's Rep 132 (Lark) at 139 (Hirst J); Precision Pools Pty Ltd v Commissioner of Taxation (1992) 37 FCR 554 at 560 (Spender J); see also Brookfield Australia Investments Ltd v Lucas Stuart Pty Ltd [2012] NSWSC 1130 at [34] (Stevenson J); Quadling v Robinson (1976) 137 CLR 192 (Quadling) at 201 (Gibbs J).
35 Whether a communication accepts the terms of an offer without modification, or instead varies its terms, is a question of construction: Quadling at 201.
36 Amendment of an offeror's offer by the offeree in a material respect is a counter-offer, not acceptance: Olivaylle Pty Ltd v Flottweg GMBH & Co KGAA (No 4) (2009) 255 ALR 632; [2009] FCA 522 (Olivaylle) at [23] (Logan J); see also Outer Suburban Property Ltd v Clarke [1933] SASR 221 (Outer Suburban Property) at 225-6 (Angas Parsons and Napier JJ).
37 However, a variation in the alleged acceptance which favours the offeror is not treated as a material variation: Ex parte Fealey (1897) 18 LR (NSW) 282 (Ex parte Fealey) at 290 (Owen J, BG Simpson J agreeing); Boreland v Docker [2007] NSWCA 94 (Boreland) at [76]-[78] (Beazley JA, with whom Mason P and Ipp JA agreed); see also Quadling at 197 (Barwick CJ) and 201 (Gibbs J).
38 Normally an apparent variation in the acceptance of the terms in the offer, or the introduction of some additional term, will prevent the purported acceptance from being an acceptance. Instead, if it relates to the subject matter of the offer, it may be a counter-offer, operating as a rejection of the original offer, revocable at any time before its acceptance but capable of creating a contract if the original offeror accepts it: see Mulcaire v Newsgroup Newspapers Ltd [2012] Ch 435; [2012] EWHC 3469 (Mulcaire) at [27] (Sir Andrew Morritt C).
39 A reply which propounds a new term is not an acceptance: Jackson v Turquand (1869) LR 4 HL at 312; R A Brierley Investments Limited v Landmark Corporation Limited (1966) 120 CLR 224 at 233-4 (Barwick CJ, Kitto and Windeyer JJ); see also Grainger v Vindin (1865) 4 SCR (NSW) 32.