The subsidiarity rule: The unjust enrichment doctrine in construction law

Purpose: The purpose of this paper is to re-examine the subsidiarity rule in unjust enrichment and challenge some of its theoretical foundations and its unqualified application in unjust enrichment law as a whole. Design/methodology/approach: The paper uses a comparative approach with South African and Brazilian laws as the main reference points, but it extends the analysis to common-law jurisdictions elsewhere. It explores the extent and limits of the applicability of the rule in claims arising from the built environment. It analyses the interaction between the subsidiarity rule and the defence of change of position. Findings: It concludes that, in three party cases, subcontractors may be able to use enrichment actions against owners to obtain an adequate redress. The exclusion of enrichment claims where there is a consensual distribution of risks and rewards normatively operates to validate any transferred benefit and eliminates any prospective normative gain or loss. However, policy-based claims for unjust enrichment can be made even in the presence of such bargains. Originality/value: The paper pioneers the analysis of subsidiarity rule in the specific context of the built environment. It presents an original examination of the interaction between the subsidiarity rule and change of position defence.