Lloyd's Maritime and Commercial Law Quarterly
DEPARTMENTS OF LAW, THE UNITY OF LAW AND THE LIMITS OF “LOCAL PRIORITY”
Sir David Foxton *
Taking its cue from Professor Ronald Dworkin’s discussion of the concepts of “departments of law” and “local priority” in Law’s Empire, this paper considers the extent to which, when seeking to resolve a disputed issue of law, courts and academics should look to other areas or “departments” of law. It also addresses the related questions of how we determine to which “department of law” a particular issue belongs, and what constitutes a “department”. These ideas are explored by reference to the relationship between law and equity, public and private law, tort and crime, and the current debate about the coherence of a legal category of unjust enrichment. The paper concludes with the suggestion that, in an age of increasing legal specialisation, we should accord less weight to the demands of “local priority” and be more ready to look for assistance outside the immediate confines of the area of law at hand.
Introduction
The subject of this paper is a methodological challenge faced, I think, by both legal scholars and judges, particularly appellate judges. It is in what legal context one should site the disputed issue of law which one is trying to interpret, and how far one should look outside that context when testing the coherence of a possible answer.1 Picking up two phrases which have recently entered legal academic discourse, I want to consider how we avoid both the bunkers2 of “category errors”,3 and the rough of “thinking in silos”.4 When I refer to “interpretation”, I use that term in its Dworkinian sense as the process by which judges and jurists ascertain what the answer to a disputed question of law is, or should be.
* Lord Justice of Appeal. This paper was prepared as a talk to the UCL Private Law Group Workshop for Early-Career Scholars on 22 April 2026.
1. In this regard, I am not concerned with coherence of outcome across different areas of law—a frequent issue when addressing how criminal and tort law interrelate—but consistency in the content of the legal rules themselves. On the former topic, see eg Matthew Dyson, “Private Coherence: Legal Reasoning Across Parts of the Legal System”, in Oxford Studies in Private Law Theory: Volume III (2025), 53. That has been a particular concern in so-called “sanctions shifting” cases in which someone seeks compensation in a private law context for a sanction imposed on them by the criminal law: Gray v Thames Trains Ltd [2009] UKHL 33; [2009] 1 AC 1339 and now Lewis-Ranwell v G4S Health Services (UK) Ltd (No 3) [2026] UKSC 2; [2026] 2 WLR 187.
2. I am assuming that classical allusions are no longer an acceptable means of describing the issue, and that a golfing metaphor is not exclusionary—although I have run into difficulty with cricket in the past. Readers should feel free to substitute an idiom of their choice,
3. My search produced 45 uses of this phrase in journal articles.
4. A mere 40, although most not concerned with the issue, with “the unity of law” clocking up a significant number of appearances.
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