This blog post has been contributed by Mr Simon Askey, Associate Dean for Undergraduate Laws, for Legal Systems and Method.
The interpretation of legislation that applies across multiple UK jurisdictions has long exposed a subtle tension within the doctrine of precedent. Courts in England and Wales have consistently acknowledged that they are not formally bound by decisions of the Scottish courts or those of Northern Ireland. Yet, in practice, judges have frequently treated such decisions as carrying enhanced persuasive weight—sometimes approaching functional binding force—particularly where the relevant statutory provisions are identically worded.
This dynamic was evident in Abbott v Philbin (1960). Although Roxburgh J articulated the orthodox position that Scottish decisions do not bind English courts, the Court of Appeal adopted a more pragmatic stance. Despite expressing reservations about the correctness of the Scottish Inner House’s judgment in Forbes, the Court nevertheless followed it in order to avoid conflicting interpretations of the same tax statute. The language of “compelling reasons” developed there implicitly elevated extra-jurisdictional authority beyond ordinary persuasive status. While the House of Lords later overruled Forbes, it endorsed the Court of Appeal’s instinct to preserve uniformity pending authoritative resolution.
This approach reappeared in Secretary of State v Deane [2010], where the Court of Appeal again regarded the synchronicity of statutory wording between England and Wales and Northern Ireland as creating a strong practical imperative for alignment, even in the absence of doctrinal compulsion.
The Jwanczuk litigation and the return of the Abbott principle
The issue resurfaced in Jwanczuk [2025] UKSC 42. The underlying legislation was materially identical across England and Wales and Northern Ireland. In O’Donnell [2020], the Northern Ireland Court of Appeal had interpreted that legislation through the lens of the Human Rights Act 1998 and concluded that the statutory scheme was discriminatory.
Faced with this, Kerr J in the High Court treated O’Donnell as persuasive authority of considerable weight, indicating he would depart only if it were “clearly wrong.” Underhill LJ, delivering the judgment of the Court of Appeal, refined this into a restatement of Abbott: English courts should ordinarily follow appellate authority from Scotland and Northern Ireland on inter-jurisdictional statutes unless there are “compelling reasons” to do otherwise. He went further still, suggesting that High Court judges, in particular, ought to be especially reluctant to deviate from other UK appellate courts.
This line of reasoning created a quasi-binding effect for decisions of other UK appellate courts. Even where an English court doubted an extra-jurisdictional authority, it was to follow it absent exceptional justification. In doctrinal terms, this elevated the persuasive force of such decisions well beyond traditional limits.
The Supreme Court re-evaluates the role of cross-jurisdictional precedent
The Supreme Court decisively rejected that approach. In a joint judgment by Lord Reed and Lady Simler, with which the remaining justices agreed, the Court reaffirmed the principle that precedent does not operate across jurisdictional boundaries. Decisions of other UK appellate courts may be influential, but they do not engage the doctrine of stare decisis; they are governed solely by practice and judicial discretion.
While acknowledging that consistency in the interpretation of UK-wide legislation is ordinarily desirable, the Court made clear that correctness takes priority over uniformity. The only exception concerns tax legislation, where historical and constitutional considerations justify requiring homogeneous interpretation. In that specific domain, the Abbott principle retains its force.
By contrast, in all other fields, the Court rejected the “compelling reasons” test and held that English courts are free to depart from extra-jurisdictional authority whenever they are persuaded that it is wrong. There is no need to meet a threshold of “plain”, “clear”, or “exceptional” error. The Court of Appeal had, therefore, erred in treating itself as constrained absent exceptional circumstances.
Doctrinal implications
The judgment in Jwanczuk recalibrates the relationship between the UK’s parallel appellate courts. It confirms that the doctrine of binding precedent is strictly jurisdiction-specific, and that practice—not doctrine—explains the historical willingness of English courts to follow Scottish or Northern Irish authority on shared statutory provisions. English courts may now engage with such decisions on a more orthodox, analytical basis: the question is simply whether the reasoning is correct. This avoids the awkwardness of determining whether an earlier decision is not merely wrong, but wrong “compellingly” or “exceptionally.”
Great