*Editors’ Note: This post is part of the ‘Unwritten Constitutional Norms and Principles Blog Series’*

It remains commonplace, both in political and public law discourse, to describe the Royal Prerogative as archaic or anachronistic. Executive power in the United Kingdom may begin with the Crown, but even the most venerated constitutional historians have long thought ‘the Crown’ is a convenient cover for ignorance. Much like the sovereignty of Parliament, the more one explores its foundations, the more one suspects the bedrock will turn out to be quicksand. As the residue of the Crown’s discretionary authority, exercised by Ministers by convention without formal or legal restraint, it has been said prerogative remains difficult to translate into the modern era, precisely because it derives from the sixteenth century. A space devoid, on some accounts, of legality itself.

Recent high-profile court cases have only bolstered this view. Miller I, for example, was accused of laying bare the crude, ‘inchoate instinctualism’ of what is and is not permissible under the prerogative. The majority were said to have invoked vague, unarticulated constitutional principles without seeking to define them, nor appeal to an authority which could. Similar criticisms have been levelled at both Miller II and the ‘Third Direction‘ case heard in the Court of Appeal. This had led some to argue there are serious theoretical shortcomings in the jurisprudence and political theory behind the British executive. Others have gone as far as to suggest there exists no articulate account of the principles that explain and justify executive power in the United Kingdom. The questions these cases have raised regarding these fundamental constitutional principles, therefore, are contentious and wide-reaching, leaving many to wonder if the British constitution is just as ‘ramshackle’ as some have implied.

The problem with this perspective is that it focuses on how these principles are understood by the judiciary in case law, resulting in a parochial, Whiggish, and overly legalistic understanding of the prerogative. Given the relative lack of case law on the prerogative, there are few examples of these principles being understood or applied legally. The legalistic perspective conflates this relative lack of judicial articulation in case law with a general ignorance of how constitutional principles condition the prerogative more widely, implying this is a legal absence that ought to be corrected. This privileges the way the judiciary engages with and understands these principles at the expense of other constitutional actors in the legislature or the executive. As a result, save for notable exceptions, scholarship has come to believe that they are somehow unarticulated in constitutional discourse as a whole, rendering the space of prerogative devoid of norms or legality. 

This can distort how the concept of prerogative is understood, providing a misleading account of both the prerogative and the substance of the principles underpinning it, as part of the political constitution. These include, in the case of prerogative related to government formation, the principle of democracy; in the case of national security prerogatives, the duty to safeguard the people and the realm; and with respect to the foreign affairs prerogative, the principles of sovereignty and nationhood. While it is true these have rarely been defined in case law, they are not poorly understood in practice. 

The war and foreign affairs prerogative is instructive on this point, demonstrating both the broad authority granted to ministers while showing that judicial understandings of these principles are necessarily limited. Unlike many other powers which have been partially or fully displaced by statute, or else fallen into desuetude, the war and foreign affairs power remains the sine qua non of the prerogative. A range of authorities outline the basic structure of this power, including works of constitutional significance by Maitland, Chitty, and Dicey, the Cabinet Manual, the Letters Patent that define the Defence Council and its subsidiary boards, and the practice of how the government organises and deploys the armed forces. Yet, somewhat ironically, the small group of legal cases that touch upon the war prerogative also provide some of the most succinct refutations of the legalists’ position. For the purpose of this short article, therefore, we explore how these cases understand the war prerogative, demonstrating the limited perspective that they provide. Moreover, we argue that by relying predominantly on this perspective, we risk ignoring the substance of how these powers are structured and operate on a day-to-day basis. 

Writing for the majority in Miller I, Lord Neuberger explicitly rebutted the legalistic understanding of prerogative, arguing that although it has been described as a ‘relic of a past age’, this should not be understood as implying it ‘is either anomalous or anachronistic’. He went on to recognise there are:

important areas of governmental activity which, today as in the past, are essential to the effective operation of the state and which are not covered, or at least not completely covered, by statute. Some of them, such as the conduct of diplomacy and war, are by their very nature at least normally best reserved to ministers just as much in modern times as in the past. 

This stems from the broader ‘foreign affairs prerogative’ outlined by F.A. Mann, which provides the basis for administering the external affairs of the United Kingdom, including war, diplomacy, and national security. Such acts are considered within the context of the defence of the realm, which has been variously described as both a principle and a prerogative. This is because all such acts are authorised for the defence of the realm, but that this thereby places a limit of reasonableness upon their exercise, concurrent with the principle that such acts must ‘maintain order’. Irrespective of this, the existence of this power has never seriously been called into question, and remains the undoubted right and duty of the Crown. Indeed, the very idea that there is no prerogative to act in defence of the realm or to keep the peace looks wholly absurd if one thinks of the logical consequences that follow from this. 

Moreover, as Lord Reid recognised in Burmah Oil although powers clearly exist for the defence of the realm, and while ‘the prerogative certainly covers doing all those things in an emergency which are necessary for the conduct of war’, these acts:

are conspicuously not discretionary or arbitrary in any typical sense. On the contrary, they are acts of necessity, performed in sudden and extreme emergency, when there is, in effect, only one thing to be done for the public safety.

Reid’s formulation suggests this power is neither arbitrary, nor the unfettered, discretionary authority of the government. Indeed, those moments where it has been exercised as if it is an arbitrary power are recalled so vividly because they gave rise to some of the gravest moments of constitutional and political crisis. Similarly, Lord Denning addressed this point in Laker Airways, writing that:

The prerogative is a discretionary power exercisable by the executive government for the public good, in certain spheres of governmental activity for which the law has made no provision, such as the war prerogative … or the treaty prerogative… The law does not interfere with the proper exercise of the discretion by the executive in those situations: but it can set limits by defining the bounds of the activity: and it can intervene if the discretion is exercised improperly or mistakenly. That is a fundamental principle of our constitution.

Denning draws heavily on John Locke’s famous formulation that prerogative is that ‘power to act according to discretion, for the public good, without the prescription of the law, and sometimes against it’. Yet he also raises the notion of ‘fundamental principle[s]’, suggesting that prerogative is not wholly immune from judicial interrogation, even if it is usually exercised to deal with ‘political questions’, beyond the proper province of the courts. 

This it interesting, for while the legalistic view often consciously contrasts itself to the Lockean position, Denning shows this definition can quite happily co-exist with the notion that fundamental constitutional principles structure and channel the exercise of the war power. This captures the essence of contemporary constitutional disagreements over the prerogative, recognising that in certain extreme cases the law may intervene if discretion is exercised in an improper manner, as in the Miller cases, without encroaching upon the essentially political nature of the prerogative. A court may simply recognise these principles to exist and decline to elaborate on them, given that their substance is created and applied in government or Parliament.

As such, the image of the prerogative as devoid of legality is, and always has been, an illusion. The controls and context may have changed. The mores of society may have morphed. But the prerogative has always been recognised as incorporating reciprocal duties and obligations without which its existence was untenable. This is not peculiar to these two cases, and has been acknowledged in an unbroken line of judicial precedent on the war prerogative. For instance, Nourse LJ notes in Northumbria that:

it is important to remember that the Royal prerogative was never regarded as a collection of mere powers, to be exercised or not at the will of the sovereign. The King owed certain duties to his subjects, albeit duties of imperfect obligation whose performance could not be enforced by legal process. Nowadays these duties are taken to be expressed in the coronation oath, whose modern form derives from the Coronation Oath Act 1688. They included a duty to protect the lives and property of the King’s subjects.

These are to be found at least in part through the duties referenced to the prerogative of protection. One might likewise recall the majority in Burmah Oil held that while the Crown had the prerogative right to requisition and even destroy property in wartime, it still owed a duty to pay for damages caused, absent the authority of Parliament. Consider also the Supreme Court of Canada’s reflections on the foreign affairs prerogative in Khadr: 

[t]he limited power of the courts to review exercises of the prerogative power for constitutionality reflects the fact that in a constitutional democracy, all government power must be exercised in accordance with the Constitution. This said, judicial review of the exercise of the prerogative power for constitutionality remains sensitive to the fact that the executive branch of government is responsible for decisions under this power, and that the executive is better placed to make such decisions within a range of constitutional options. The government must have flexibility in deciding how its duties under the power are to be discharged.

Indeed, arguably the strongest checks on the prerogative in recent times have been the rights of the individual. While statute can grant the executive authority to violate rights in certain circumstances, prerogative appears far more constrained in this regard.

This short history of the defence of the realm gets at the heart of much confusion around the point raised by Miller I and II. Cases like De Keyser, Burmah Oil, Northumbria and Khadr provide orthodox snapshots of the prerogative; windows into a world governed by principle, custom, practice, and convention, which have always structured its existence, scope, and extent, but whose wider substance is not touched upon precisely because it is not relevant to the particular case at hand. 

This is often in direct conflict with the view presented by the legalists, who suggest that these principles ought to be better understood from the judicial perspective. This misconstrues both the problem and the solution. There is neither a legal absence at play nor a lack of understanding of the principles in general. The supposed lack of understanding comes from the limited and peculiar cases on which the court has been asked to rule, as these principles have been, and continue to be, developed by the political practice of Parliament and Ministers, rather than in the courts. As Loughlin observes, the prerogative has evolved alongside the principles of statecraft and political right; while it may be more difficult to see this in a legal world dominated by a court-centric approach, this is no less true today. This does not necessarily make these powers non-justiciable or matters improper for the courts on occasion, as the case law demonstrates. Rather, it shows that the prerogative is normally best regulated outside of the courts, where these principles are developed and operate on a daily basis. 

The point here is not to diminish the importance or value of the judicial perspective. On the contrary, as the above makes clear, the judiciary has often provided excellent articulations of several principles underpinning the prerogative. Rather, it is to show that the case law which touches on prerogative is limited, peculiar, and extreme, and that it is often unhelpful for our general theoretical understanding of how these powers operate and how they are structured. The idea is to shift the focus from looking at how these principles are understood and applied by judges in a given case to how they are created, sustained, and applied by the government and Parliament. As has recently been noted, the executive and the legislature still possess broad discretion when engaging in the practical interpretation and application of prerogative powers, regardless of the relative expansion of judicial involvement in recent years. The courts usually restrict themselves to demarcating the limits of such powers, leaving their exercise untouched. As some have begun to recognise, attention should be focused on how executive and legislative actors go about this task of interpretation and application, rather than the illuminating but necessarily narrow interpretations found in the courts. Constitutional inquiry would be all the richer for it. 

This perspective advocates a move away from the legalistic view, placing primacy on the attitudes of executive actors and Parliamentarians toward both the prerogative and the principles that structure it. When viewed through this historical and political lens, the principles of prerogative are everywhere seen, embodied in the day-to-day practice of statecraft through Government and Parliament. To view the prerogative through the lens of the judiciary is to miss a great part – perhaps the most important parts – of the concept itself.

Daniel Skeffington is a Doctoral Candidate, Department of War Studies, King’s College, London. daniel.skeffington@kcl.ac.uk

Philippe Lagassé is Associate Professor and Barton Chair, Norman Paterson School of International Affairs, Carleton University. philippe.lagasse@carleton.ca

(Suggested citation: D. Skeffington and P. Lagassé: ‘Principle, Practice, and Prerogative’, U.K. Const. L. Blog (23rd May 2024) (available at https://ukconstitutionallaw.org/)