Knowledge and unconscionability in a unified estoppel

The prevailing wisdom in the Australian commentary is that 'unconscionability' is a key element required to establish an equitable estoppel.' The inclusion of this undefined and somewhat mysterious element distinguishes equitable estoppel from its common law counterpart, the elements of which have always been clearly defined. That difference is clearly a significant barrier to the unification of the two sets of principles. The aim of this article is to attempt to uncover what it is involved in the unconscionability element, and to attempt to reconcile the common law and equitable doctrines of estoppel in this regard. The article takes as a starting point the notion that the equitable and common law doctrines of estoppel should be ~ n i f i e d , ~ and attempts to assist in facilitating that unification by reconciling an important difference between the two doctrines. Although a number of eminent jurists have suggested that unconscionability is a concept that cannot, and should not, be defined,3 it is important to do