The judgments of the plurality and Gordon J in the recent High Court decision of Thorne v Kennedy have undoubtedly altered the prior law relating to undue influence in Australia. But the most significant alterations, which are twofold, are both unacknowledged and unsupported by justificatory reasons. First, undue influence is presented as a single concept not having different forms, or involving different principles, across the traditional categories or ‘classes’ of undue influence. Accompanying that is surreptitious abandonment of the ‘fiduciary’ explanation for the second, ‘relational’ category of undue influence, prominent in antecedent authorities such as Johnson v Buttress. This is demonstrated, in particular, by the unacknowledged and unexplained evaporation of the ‘prophylactic’ function and content of the traditional ‘presumption’ of undue influence. But nowhere do their Honours openly address and credibly respond to the conventional rationale – the generic policy foundations – that originally motivated the strict fiduciary regulatory regime in those cases where the presumption traditionally operated. Second, as a single concept, undue influence is, in stark contrast to unconscionable dealing, rationalised as a ‘plaintiff-sided’, ‘impaired-consent’ ground of relief. Although prior dicta existed to support such an outlook on undue influence, those dicta, themselves of dubious lineage, were accepted in Thorne without pause or explanation, and certainly without acknowledgment of a strong current of senior judicial opinion to the contrary, both domestically and abroad. We are left, then, in the wake of Thorne, with an unexplained disjunctive rationalisation of two equitable exculpatory doctrines that are nevertheless acknowledged to be ‘closely related’. This does not augur well for the logical taxonomisation of those sibling doctrines, both as between themselves and relative to other exculpatory categories that equally function to discipline the abuse of unofficial power-vulnerability relationships or encounters in connection with bilateral transactions.
Rick Bigwood, The Undue Influence of ‘Non-Australian’ Undue Influence Law on Australian Undue Influence Law: Farewell Johnson v Buttress? Part I (2018) 35 Journal of Contract Law 56.