121 As has been often observed, the Courts have not laid down a clear dividing line between an equitable interest in property and what is described as "a mere equity". The difficulties of categorisation were recognised well before the decision in Phillips v Phillips and have not been resolved despite much erudite judicial and academic discussion since then: see e.g. Double Bay Newspapers at 423E; Megarry & Wade "The Law of Real Property" (2000) 6th Ed, para.5-013; Snell's Equity (2000) 30th Ed, para 2-05; (1955) 71 LQR 480; Meagher Gummow & Lehane Equity Doctrines and Remedies (1992) 3rd Ed, paras.427ff.
122 Equitable, or proprietary, interests and "mere equities" alike depend for their very existence upon the fundamental concept that equity acts in personam and that the rights which it recognises and enforces are not rights in rem but rights in personam. So, for example, the beneficiary of a bare trust of land is said to have an equitable interest in the land because an equity court, acting upon the conscience of the trustee, will compel the trustee to deal with the land in a certain way for the benefit of the cestui que trust. Likewise, the purchaser of land under an uncompleted contract for sale is said to have an equitable interest in the property, but only because it is tacitly assumed that a court of equity will grant specific performance of the contract. In examples such as these, the equitable interest is commensurate with the availability and extent of the corresponding right in personam: see e.g. Glenn v Federal Commissioner of Land Tax (1915) 20 CLR 490, at 503-504 per Isaacs J; Central Trust and Safe Deposit Co v Snider [1916] 1 AC 266, at 272; Brown v Heffer (1967) 116 CLR 344, at 349; DKLR Holding Co (No 2) Pty Ltd v Commissioner of Stamp Duties [1980] 1 NSWLR 510, at 518ff.
123 It follows that if the equity court would not enforce the right in personam - where, for example, it has been lost by acquiescence, laches, delay or some other circumstance affording a defence - then the equitable interest might either never have existed in the first place or might have ceased to exist: see Central Trust and Safe Deposit Co at 272.
124 A right enforceable in personam in equity confers an equitable, or proprietary, interest only when there is a nexus of sufficient propinquity between the right and the specific property to which the right relates. What is a nexus of sufficient propinquity is the conundrum. It has been recognised that "there is some circuity involved in finding the starting point for the existence of … an equitable interest, the problem being to isolate as the initiating factor the proprietary interest or the right to enforce the interest … This problem is almost a jurisprudential mystery" : per Kearney J in Burns Philp Trustee Co Ltd v Viney [1981] 2 NSLWR 216, at 223.
125 Many definitions of an equitable interest have been attempted and found wanting. For example, in National Provincial Bank Ltd v Ainsworth [1965] AC 1175, at 1248, Lord Wilberforce identified such an interest as being one which was "definable, identifiable by third parties, capable in its nature of assumption by third parties and [having] some degree of permanence or stability" . That definition has been much criticised: see Meagher Gummow & Lehane Equity Doctrines and Remedies (1992) 3rd Ed, para.428. There is probably no point in attempting any universal definition. As Kearney J said in Burns Philp Trustee Co Ltd v Viney , at 223-224:
"… there is an obvious difficulty in endeavouring both to analyse and to formulate any general principle in this area of the law. The administration of equity has always paid regard to the infinite variety of interests and has refrained from formulating or adhering to fixed universal and exhaustive criteria with which to deal with such varying situations. The approach traditionally adopted by equity has been to retain flexibility so as to accommodate the multitudinous instances in which fundamental equitable rules fall to be applied."
126 Like an "equitable interest", a "mere equity" is a slippery creature. It can be cornered and illuminated by example but not captured and confined by definition. For present purposes, the most illuminating example is found in the Latec Investments case. There, a mortgagee fraudulently exercised a power of sale, so that as against the mortgagee and the collusive purchaser the mortgagor had a right in equity to set aside the conveyance. However, the rights of a third party had intervened in the meantime so that the competition was between the mortgagor, claiming an equitable interest in the land which was prior to that of the third party, and the third party who claimed a subsequent equitable interest acquired for value without notice of what it said was the mortgagor's "mere equity".
127 There was disagreement between Kitto and Taylor JJ as to whether the mortgagor had a prior equitable interest in the property. Kitto J was of the view, on the authority of Phillips v Phillips , that the mortgagor had to make good its right in equity to have the fraudulent conveyance set aside before the mortgagor could be said to have an equitable interest in the land, namely, its equity of redemption. As between the mortgagor and the third party, the competition was, according to his Honour, between a "preliminary equity" - that is, a claim to set aside the conveyance for fraud - and an admitted subsequent equitable interest. His Honour was of the opinion that Phillips v Phillips compelled the conclusion that the "preliminary equity" was a "mere equity" which could not compete with the subsequent equitable interest acquired for value without notice: at 277-279.
128 On the other hand, Taylor J was of the view that the mortgagor had never been deprived of its equitable interest in the property by the voidable fraudulent conveyance. On the authority of cases decided both before and after Phillips v Phillips , his Honour concluded that the owner of an equitable interest in property who is induced by fraud to transfer it continues to retain that equitable interest: it does not cease upon the transfer and then come into existence again when the transfer is set aside: at 281-284.
129 However, Taylor J concluded that the true principle enunciated in Phillips v Phillips was simply that where the person entitled to a prior equitable interest requires the assistance of a court of equity to remove an impediment to his or her title as a preliminary to asserting it, the court will not interfere if a third person has acquired an equitable interest in the property for value without notice before the prior equitable interest holder comes to the court for assistance: at 286.
130 The approach of Menzies J was to attempt to reconcile the two apparently conflicting streams of authority relied upon by Kitto and Taylor JJ. His Honour would recognise that an equitable right could be a "mere equity" in the sense adopted by Kitto J for the purpose of a priority contest with an equitable interest and yet could be an "equitable interest" for the purpose of transmission by devise or assignment: at 290-291. In the result, therefore, Menzies J agreed with the position taken by Kitto J.
131 Latec Investments has been judicially considered on very many occasions and I will not contribute yet another exegesis. My own view, which reflects the approach taken by Menzies J, is that Phillips v Phillips can be explained as a policy decision rather than a decision resting on distinctions in the qualities of various equitable rights. The policy is simply this: where the holder of a prior equitable interest needs the assistance of the equity court to perfect his or her title to it, that equitable interest will be defeated if, before the title is perfected, a third party takes an equitable interest for value without notice.
132 Perfecting the title to an equitable interest does not mean resolving a dispute as to its existence in the first place, as where, for example, parties disagree as to whether a document has created an equitable charge and a declaration is sought from the equity court. Perfecting the title means seeking an equitable remedy without which a previously existing equitable interest would be lost.
The nature of the Mills' interest