Constructive Trusts, Unconscionability and the Necessity for Working Criteria

This article considers two recent UK Supreme Court decisions and their parallel Australian developments, in which the equitable concepts of ‘constructive trusts’ and ‘unconscionability’ have respectively been the subject of detailed examination. The analysis of these seemingly disparate fields reveals two shared truths. The first is the inherent difficulty but also acute necessity of taxonomical reasoning in the law and the substantive
significance of our organising categories, particularly when engaged in analogical reasoning. The second and related point is that equitable concepts stated at a very high level of generality cannot meet the need for specific working criteria at the practical level of decision-making. While this necessity has been acknowledged and acted upon by courts in both jurisdictions in the sphere of constructive trusts, a contrary view appears to
underpin the elevation of unconscionability as the determinative criterion in the fields of rescission and restitution for mistake. The analysis concludes that, notwithstanding, it remains necessary and possible to identify concrete, coherent and clear guiding factors for relief in such cases.