A comprehensive review, or what has been variously described as the classification or mapping or taxonomy, of constructive trusts would require analysis of areas of law as diverse as vendor and purchaser transactions, the perfection of imperfect gifts, fully secret and half secret trusts, breach of fiduciary duty, and accessory liability for breach of trust, among several others. The search for an acceptable, universally acknowledged, principle for the establishment of a constructive trust, which gives coherence to past decisions and provides a clear guide for the future, will certainly prove elusive in relation to the many different areas of law and fact in which constructive trusts arise.

The question to be pursued in this article has the merit of simplicity even if the response to it proves somewhat complex. The question is this: is law truly a social science? This may seem an odd question to many in the common law world since it is not uncommon, at least in England, for law schools to find themselves located in faculties of social science. Moreover there are a number of individuals, perhaps a considerable number in common law departments and faculties throughout the world, whose research and scholarship undoubtedly qualifies as social science research. So, before one can even begin to reflect upon the question to be pursued in this paper, a preliminary question must first be asked. Why should one wish even to pose the question?

I will not draw a distinction between biological and non-biological – we are not buying Persil or Daz (Stephen Quinn)

According to Ronald Dworkin, all judges are by necessity philosophers, and no judge is a better philosopher than Hercules. This superhuman jurist understands that law's empire embraces not just decisions about rights made in the past, but also rights implicit in the theory of political morality that those decisions presuppose. He is able to survey all of the diverse laws within a system and then construct a comprehensive theory of political morality that shows those laws to be as coherent and unified and just as they can be. From this theory not only will right answers in hard cases emerge, but the value of integrity-the value of extending to everyone the rights extended to some so that equal concern and respect is secured for all-will be honoured. In contrast, Herbert, the judge Dworkin introduces as Hercules' nemesis, thinks that law ends just at the point where hard cases begin. Herbert is intellectually flatfooted in the face of legal challenges that Hercules can handle adeptly and accurately.

The dilemma facing the law when two innocent parties have suffered at the hands of a wrongdoer is well known and arises acutely in the context of the sale of goods. Typically, in the classic simple three party situation: the owner of goods either gives goods to or has goods stolen by a rogueseller who purports to sell them to an innocent third party buyer. Both the owner and buyer of the goods may well have a personal claim against the seller, but if the seller has either disappeared or has no money that personal claim may well be worthless. As a result, the question of who is entitled to the goods themselves is likely to determine which party will suffer as a result of the seller's actions. The crucial issue is who in this situation is entitled to the goods: this is a question of conflict of title or priority. Who has a better title to the goods, the owner or the buyer?