Lloyd's Maritime and Commercial Law Quarterly
DOUBTING THE SUBSIDIARITY OF UNJUST ENRICHMENT
Mat Campbell *
Courts and commentators frequently use the noun “subsidiarity” and the adjective “subsidiary” to help explain certain of unjust enrichment’s relations with other areas of law and legal institutions—especially property, contract, and statute. However, the vocabulary of subsidiarity is unsuited for that purpose. It should disappear from unjust enrichment discourse. After its Introduction, this paper proceeds in four Parts. Parts II and III analyse accounts of unjust enrichment as subsidiary to property and contract. The instances in which unjust enrichment claims are said to be subsidiary to property and contract are ones in which a given enrichment is not unjust in the first place. They are situations where, as a matter of law, no unjust enrichment claim actually exists to be subsidiary to any other claim or institution. They cannot logically, therefore, represent examples of the so-called subsidiarity of unjust enrichment. They are better explained through the spectrum of the “unjust question” in the unjust enrichment inquiry. Part IV applies the same arguments to the interaction of unjust enrichment and statutes which are entirely inconsistent with unjust enrichment claims. It also demonstrates that unjust enrichment is not subsidiary to statutes which, though not exclusive of unjust enrichment, nevertheless alter its normal operation. Part V concludes.
I. INTRODUCTION
Distinguished scholars have remarked that unjust enrichment “always seems to raise the issue of subsidiarity”.1 This involves “questions of the relationship between [unjust] enrichment and other parts of the law”.2 More specifically, it concerns the constraint
* Lecturer, School of Law, University of Glasgow. An anonymous referee gave valuable comments. Bobby Lindsay commented perceptively on an earlier draft. I am further indebted to others too numerous to list. The usual disclaimers apply.
The following abbreviations are used:
Campbell, “Subsidiarity”: M Campbell, “The Subsidiarity of Unjust Enrichment: Anglo-Franco-Scots Perspectives” (PhD Thesis, Edinburgh, 2019), available at https://era.ed.ac.uk/handle/1842/35761; Virgo, Principles: G Virgo, The Principles of the Law of Restitution, 3rd edn (Oxford, 2015).
1. D Johnston and R Zimmermann, “Unjustified Enrichment: Surveying the Landscape”, ch.1 of D Johnston and R Zimmermann (eds), Unjustified Enrichment: Key Issues in Comparative Perspective (Cambridge, 2002), 29.
2. HL MacQueen, “Unjustified Enrichment, Subsidiarity and Contract”, ch.11 of V Palmer and E Reid (eds), Mixed Jurisdictions Compared: Private Law in Louisiana and Scotland (Edinburgh, 2009), 329.
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