1. Introduction

Recent public law cases concerning dualism––the operative divide between international and domestic jurisprudence––have prompted renewed debate about the constitutional role of judicial review in the United Kingdom. At first glance, decisions such as R (FDA) v Minister for Cabinet Office [2024] EWHC 1729 (Admin); and R (Al Haq) v Secretary of State for Business and Trade [2025] EWCA Civ 1433 appear to signal a retreat from the more dualism-sceptical trajectory associated with earlier authorities like R (Atamewan) v Secretary of State for the Home Department [2013] EWHC 2727 (Admin), R (Galdikas) v Secretary of State for the Home Department [2016] EWHC 942 (Admin), and R (KTT) v Secretary of State for the Home Department [2021] EWHC 2722 (Admin). Yet this interpretation is too hasty. What the recent case law reveals is not a straightforward re-entrenchment of orthodox dualism, but the consolidation of a more procedurally conservative judicial posture centred on coherence, justification, and institutional restraint.

2. The State of Dualism

Judicial review case law on the principle of dualism—the idea that domestic and international law are distinct systems of norms, and international obligations therefore require domestic implementation––is undergoing some changes. Tracing cases from 2003 to 2024, I revisit an apparent trend towards narrowing the dualist divide: that the courts have been, arguably, less dogmatic about refusing judicial scrutiny of unincorporated treaties. Some more recent decisions since 2024––FDA and Al-Haq in particular––seem to, on the face of it, reverse this trend. I argue that this would be the wrong interpretation. FDA and Al-Haq do not truly reverse this trend. Instead, they complicate the picture. We can understand these developments better by looking at how the case law on dualism has come to reflect a broader small-c conservative turn in British jurisprudence, emphasising procedural orthodoxy over value-driven reasoning. I explain and defend this shift while hinting at the normative principles operative in the background.

The argument advanced here is that recent developments in the dualism case law can only properly be understood against the backdrop of a broader constitutional shift within the judiciary itself. Over the last years––and in any case since Miller II––the senior courts have increasingly adopted a more restrained conception of judicial authority. A number of commentators have observed this movement already. The Supreme Court today appears markedly less willing to engage in overtly value-driven constitutional reasoning––which famously marks the crux of the Waldron-Dworkin debate on the legitimacy of judicial review in democracies––and more inclined to emphasise constitutional boundaries, procedural orthodoxy, and deference to political institutions.

The case against judicial review in democracies highlights the lack of democratic authorisation of judicial decision. What is particularly rejected as anti-democratic is what is sometimes called ‘judicial activism’: the courts interfering politically and beyond their constitutional bounds. What is interesting about the dualism case law, as I will explain in some more detail below, is how the courts are seemingly mindful of their constitutional limits, and have thus incrementally worked their way towards a judicial review practice that still holds the executive accountable but refuses to issue value-judgments on political matters in the process.

That broader development matters for understanding the new dualism authorities. Read superficially, the line of cases from Atamewan through to KTT may suggest a gradual erosion of the dualist divide. Courts appeared increasingly willing to review domestic policy against unincorporated international obligations. More recent decisions, however, especially FDA and Al-Haq, seem at first sight to restore the traditional firewall between domestic and international law.

But the deeper constitutional logic running through these authorities is not really about dualism alone. Rather, the cases reveal the emergence of what might be described as a politically sensitive form of judicial review (PSJR): a mode of review focused on the coherence and intelligibility of executive action. Under PSJR, courts are not directly enforcing treaty obligations as domestic law. Instead, they are asking whether executive power is being exercised consistently with the Government’s own normative commitments.

This is a critical distinction. The courts are not abandoning parliamentary sovereignty or transforming treaties into directly enforceable constitutional standards. Rather, they are increasingly unwilling to permit the executive to rely upon international norms abroad while simultaneously disregarding them domestically without adequate justification. The target of review is not international law as such, but inconsistency in the exercise of public power.

The roots of this development can be traced back to ABCIFER in 2003. Although the Court of Appeal ultimately rejected the challenge to the compensation scheme for British civilian internees, the case articulated an important administrative law principle: executive criteria must remain “rationally connected” to the objectives they purportedly serve (at 40). Policies lacking such coherence may become unlawful.

This concern with coherence later became central in the trafficking and migration cases. In Atamewan, the High Court reviewed Home Office guidance concerning the definition of a “victim” under the Council of Europe Convention on Action against Trafficking in Human Beings (ECAT). Crucially, the Secretary of State accepted that if the guidance purported to implement ECAT, it would be unlawful if it failed genuinely to do so. This became what later cases termed the ‘Atamewan concession’.

The constitutional significance of that concession is significant, but often overlooked. Closer scrutiny of the principles operational in Atamewan yield an interesting view, chiming with the (newly found) procedural conservatism of the English courts.  The court was not treating ECAT as directly enforceable domestic law. Rather, the executive had voluntarily adopted a policy designed to secure treaty compliance, and administrative law required consistency between the stated aim and the policy’s actual operation. The principle is one of epistemic coherence across executive political power: one and the same executive cannot, without damage to its legitimacy, endorse or enforce differing or conflicting norms across the domestic and international domains.

3. Coherence Across Exercises of Political Power

This takes us to the hidden normative dimension of these cases. Both the modern turn towards constitutional conservatism, and its expression in judicial review case law, I suggest can be understood through the lens of political realism associated with thinkers such as Max Weber. It tracks an intuition: inconsistent political action lacks pro tanto legitimacy. Political power is not merely exercised, but must be intelligible to be recognised as legitimate authority.

This conceptual scheme is developed most clearly in the work of moral and political philosopher, Bernard Williams, whose account of legitimacy centres on what he has called the ‘Basic Legitimation Demand’: political authority, on this view, must “make sense” to those subject to it. Political power must present itself as intelligible and justifiable.  On this account, the intuition that the inconsistent exercise in political power is pro tanto illegitimate follows effortlessly. Where the executive advances one set of normative commitments internationally but departs from them domestically, it risks failing to “make sense”. As a principle of epistemic hygiene, any claim to legitimacy of such political power may be challenged and rejected. Such inconsistency is not merely politically suspicious; it is epistemically flawed, reflecting a breakdown in the intelligibility of political authority.

Meanwhile, within the constitutional architecture of shared governance, divided into its Montesquieuian compartments, it will fall on the courts to offer this course of epistemic review of executive action. Such a view of the role of courts I submit sits squarely within constitutional conservatism. It is considered conservative because achieving consistency is seen as both the upper limit of judicial power and the goal of judicial review. It is within this conservative stance—that political power must remain intelligible as legitimate authority—that the emergence of the politically sensitive form of judicial review (PSJR), the normative test for breaches of dualism, has its foundation. At its core lies a minimal but powerful normative demand: that exercises of executive power be capable of justification. And that presupposes consistency across expressions of political power, in statute, treaty, policy, or elsewhere. And the courts are its designated arbiters.

What is threshold of such inconsistency as to trigger judicial review, one may ask? If we look into FDA, for instance, the breach of international commitments is communicated to civil servants through policy implementation. Yet what constitutes a “clear” signal remains uncertain. FDA confirms that Parliament can explicitly instruct civil servants to disregard international law, but where the threshold lies is still unclear. There is likely too little case law to define it with precision. For now, the clearest signal appears to be a direct conflict between domestic and international obligations, though future cases may well push that threshold lower.

4. New Case Law on Dualism

That logic was developed further in Galdikas. Sir Stephen Silber held that domestic policy could indeed be assessed against ECAT where the Government itself had chosen to structure policy around compliance with the Convention. Again, the reasoning was not fundamentally anti-dualist. The courts were not piercing the dualist firewall by incorporating treaty obligations through judicial creativity. Instead, they were enforcing coherence in executive decision-making.

KTT reinforced the same idea. The High Court held that Home Office guidance concerning leave to remain decisions was unlawful because it failed properly to reflect Article 14(1) ECAT, despite purporting to do precisely that. What mattered was not the direct domestic force of ECAT itself, but the inconsistency between the executive’s declared normative commitments and the substance of its policy.

Taken together, these authorities seemed to reveal a gradual narrowing of the dualist divide. Yet it is important to recognise what was actually occurring. The courts were not rejecting dualism in Lord Kerr’s expansive sense, expressed in R. (J.S.) v Secretary of State for Work and Pensions [2015] UKSC 16 at [254], where he suggested that “the time has come for the exception to the dualist theory”. Rather, they were developing a thinner and more procedural principle: that exercises of public power should remain intelligible and internally coherent.

5. Widening the Dualist Divide?

On its surface, FDA however seems to have been a reversal of this trend towards dualist-scepticism. The litigation concerned Cabinet Office guidance issued in the context of the Rwanda removal policy. The guidance stated that civil servants implementing ministerial decisions would continue to act lawfully even where those decisions conflicted with interim Rule 39 indications issued by the European Court of Human Rights.

The claimants argued that this position was inconsistent with the Civil Service Code’s requirement that civil servants “comply with the law” (at 1), including relevant treaty obligations. The High Court rejected the challenge and reaffirmed orthodox constitutional principles: under parliamentary sovereignty and dualism, unincorporated treaty obligations remain politically rather than judicially enforceable.

At first sight, FDA appears to mark a decisive retreat from the earlier line of authorities. Yet on closer inspection the case is better understood as clarifying the limits of PSJR rather than abandoning it. In the earlier ECAT cases, judicial review became possible because the executive purported to implement treaty obligations while simultaneously acting inconsistently with them. In FDA, by contrast, there was no such incoherence. Parliament and ministers had openly and deliberately chosen to proceed notwithstanding Rule 39 measures. The inconsistency which drove the previous cases was ironed out––international obligations were disapplied to avoid a misalignment of domestic decisions. Whether or not one agreed with that choice politically, the relevant constitutional actors had acted consistently. This reflects the normative principle of political coherence I alluded to above: we expect political actors to not be Janus-faced; to speak with one voice, domestically and internationally.

In FDA, to avoid that looming misalignment, the executive simply decided to halt its international commitments in favour of domestic political agency. In its judicial review, the court therefore did not retreat from the principle underlying PSJR. It simply recognised that the justificatory defect present in KTT and Galdikas was absent. The Government was not covertly departing from its stated commitments; it was explicitly acknowledging and politically owning the departure.

The same constitutional logic also illuminates Al-Haq, though in a more complicated form. The litigation concerned arms export licences linked to the F-35 programme during the Israel–Gaza conflict. Human rights groups argued that the United Kingdom was obliged to suspend exports because there existed a clear risk that the equipment could facilitate serious violations of international humanitarian law.

The claim relied heavily upon the Government’s own Strategic Export Licensing Criteria, particularly Criterion Two, which prohibits exports where there is a clear risk of facilitating violations of international humanitarian law or human rights obligations. Initially, the structure of the claim resembled the earlier ECAT authorities. The Government appeared to have adopted domestic policies reflecting international legal standards and could therefore seemingly be challenged where those standards were inconsistently applied. Yet the litigation raised a much deeper issue. The Government argued that suspending licences would jeopardise broader strategic obligations associated with the multinational F-35 programme, NATO defence arrangements, and wider alliance commitments. The dispute therefore no longer concerned merely the relationship between domestic policy and international law. Instead, it involved competing international obligations themselves.

This transformed the constitutional nature of the case. The question ceased to be whether domestic policy cohered with international commitments and became instead whether courts could adjudicate between rival conceptions of the United Kingdom’s international legal responsibilities. The Court of Appeal answered firmly in the negative. Questions concerning arms exports, alliance structures, foreign affairs, and geopolitical strategy were treated as matters constitutionally entrusted to the executive rather than the judiciary.

The court reiterated the orthodox principle that unincorporated international obligations are generally not domestically enforceable absent legislative incorporation. But more importantly, Al-Haq exposed what might be termed a “meta-dualist” problem: who decides how conflicts between international norms themselves should be resolved?

The claimants effectively invited the judiciary to recognise a hierarchy of international obligations in which humanitarian duties would take precedence over strategic defence commitments. Yet constitutional conservatives are naturally sceptical of such exercises. There exists no clear judicially manageable standard for ranking competing international commitments without judges inevitably drifting into substantive political and moral reasoning.

6. Summary

In summary, it may be emphasised that recent decisions such as FDA and Al-Haq do not represent a straightforward return to strict dualism, despite appearances. Having traced developments from ABCIFER through Atamewan, Galdikas, and KTT, I have identified the emergence of a form of politically sensitive judicial review (PSJR), under which courts scrutinise inconsistencies between the executive’s international commitments and its domestic policies without directly enforcing unincorporated treaties. Rather than signalling judicial activism, this trend reflects a broader movement towards constitutional conservatism within British public law characterised by procedural orthodoxy, institutional restraint, and renewed emphasis on parliamentary sovereignty. Drawing on the political realism of Max Weber, I also alluded to the idea that this development is normatively defensible because it grounds judicial review not in substantive value-based reasoning risking, as Jeremy Waldron has argued, replacing executive authority with judicial activism, but in a thin procedural demand that exercises of political power remain coherent, intelligible, and capable of justification.

Adrian Kreutz is an Assistant Professor of Political Science at the University of Amsterdam and Visiting Fellow at the British Institute for International and Comparative Law.

(Suggested citation: A. Kreutz, ‘Dualism, Constitutional Conservatism, and Politically Sensitive Judicial Review’, U.K. Const. L. Blog (9th June 2026) (available at https://ukconstitutionallaw.org/))