Coherence and Illegality in Private Law


For more than a century, courts have struggled to identify a satisfactory basis for determining whether a plaintiff’s claim is defeated because of their illegal conduct.

Historically, statements can be found to the effect that illegality in the circumstances giving rise to liability provides an automatic bar, but on the whole this view has been rejected. Nevertheless, it has been consistently recognised that illegality can sometimes negate what is otherwise a valid claim, although there has been disagreement about when it will have this effect. In recent times, final appellate courts in Australia, Canada and the UK have all identified the need to preserve the coherence or consistency of the law as the basis of the illegality doctrine.

Notwithstanding this agreement, there remain substantial, lower-level differences between them in applying the concept of ‘coherence’. I will examine these different approaches, and identify which provides the best understanding of the notion of coherence in the law.


Andrew is a PhD candidate at the TC Beirne School of Law, University of Queensland. Andrew graduated with an LLB from the University of Queensland in 2015, and commenced his PhD in 2016.

His research examines the concept of ‘coherence in the law’, as relied on by the High Court of Australia. It seeks to understand this concept and identify its possible normative foundations. He is interested in all aspects of private law and general legal theory, and has a sideline interest in moral philosophy and the nature of reasons.