From Only the 'Bottom-up'? Legitimate Forms of Judicial Reasoning in Private Law

Abstract

This article explores the dichotomy between ‘bottom-up’ and ‘top-down’ legal reasoning in the private law context. It considers the High Court of Australia’s recent allegations that: first, ‘top-down’ legal reasoning is illegitimate in private law judicial decision-making; secondly, any arguments adopting this reasoning structure are unacceptable, such as those deriving from the Birksian model of unjust enrichment; and, thirdly, as a result unjust enrichment methodology exhibits dangerous features and leads to adverse consequences. This article contests those allegations. It argues that the meaning of ‘top-down’ legal reasoning is unclear. The concept may involve reasoning that is legislative, theoretical or prescriptive in nature. If the phrase means legislative or prescriptive reasoning, its judicial use is indeed illegitimate, but the Birksian unjust enrichment methodology does not adopt it. Conversely, if the phrase means theoretical reasoning, then the Birksian school of thought indeed adopts this method, but legitimately so. The article next contends that the Court’s allegations of danger and adverse consequences do not support its claims of illegitimacy. The unjust enrichment approach ‘fits’ well with history, seeks to avoid fictions, and creates logical unity and coherence. The article concludes that Birksian unjust enrichment reasoning merely applies orthodox judicial techniques.