The Prerogative Power of Government Power to Trigger Article 50? – A Lapse of Reason

A constitution is a set of rules, which ‘establish and regulate or govern the government’[1]. The UK’s constitution is no exception to these rules. Despite its uncodified and notoriously flexible nature[2], these rules, which make up the constitution have had significant influence on the tripartite of judiciary, executive and legislative bodies, which make up our government.  The Royal prerogative has been defined by A.V Dicey as ‘the remaining portion of the Crown’s original authority’[3]. This Prerogative is a long standing principle, providing that the Crown may negotiate treaties and the conduct of foreign affairs where these powers are not taken away by express words of a statute[4].

The extent of these residual discretionary powers is brought under review in Miller, wherein it was decided that major changes to UK constitutional arrangements can not be achieved by Minsters alone by virtue of their prerogative powers[5]. This is problematic; it is a fundamental right of the executive to, as Lord Templeman put, to ‘, conclude, construe, observe, breach, repudiate or terminate a treaty.’[6] These prerogative powers are a right of the executive that the judgement in Miller wrongfully infringes. This infringement of the royal prerogative misbalances the powers of government bodies – this is ultimately unconstitutional.  This essay will discuss the majority judgement in Miller, specifically, the wrongful application of the basic concepts of constitutional law with regard to its treatment of the scope, limits and operation of prerogative powers. I will deduce the integrity of the reasoning given in Miller and evaluate the implications of this case for the prerogative, before finally proposing solutions to the questionable trajectory of the constitution.


Changing Common Law through Prerogative 

The prerogative powers of the crown to negotiate the treaties needed to exit the EU, according to Miller, are limited by a principle of the constitution, Parliamentary Sovereignty. This places Parliament as the supreme legislative authority in the United Kingdom, and it is thus only for Parliament to create, edit and dissolve laws[7]. In addition to this, the executive cannot use their prerogative powers to change any part of the common or statue law. This follows the judgement in the Case of Proclamations where it was held ‘the King…cannot change any part of the common law, or statute law, or the customs of the realm’[8]. Moreover, Article 1 of the Bill of Rights 1689 provides that the exercise of the Crown’s prerogative must be compatible with legalization and the common law[9]. This essentially limits the use of the executive’s Royal Prerogative to that which cannot infringe upon Parliamentary Sovereignty. This is deduced by the majority in Miller to mean that the Government cannot trigger any treaty would result in the withdrawal from the EU, as much of our current law is derived from here[10].

This appears to be a straight forward application of constitutional principles, however the issue is much more complex. The dualist theory of international relations holds that treaties ordinarily have effect only on the international plane unless incorporated into domestic law as was described by Peplow[11]. In light of this, the creation or removal of a treaty can have no direct effect on domestic law without steps first being taken to incorporate it into domestic law. It is thus illogical to conclude that the invocation of article 50 by the executive could change any part of the domestic law. And so the executive would not be acting contrary to constitutional principles in acting on their prerogative powers to withdraw existing EU treaties.


Pulling the Trigger: Invoking Article 50 

It was contended that invoking article 50 would ‘pre-empt the decision of Parliament. Lord Pannick presented this argument using an analogy, stating ‘pulling the ‘trigger’ would inevitably result in the bullet hitting the target.’[12]. Clearly, once article 50 is invoked by the executive there will be a trajectory towards leaving the EU which would, eventually, alter UK law. This could be argued to put Parliament in a situation whereby they have no authority, leaving their sovereignty infringed. Because of this it was thus deduced invoking article 50 was not within the scope of the Royal Prerogative and Parliamentary approval would be necessary first.

The validity of this argument is limited. Firstly, this statement implies that once Article 50 is ‘triggered’ it cannot be withdrawn. This is a common presumption throughout the case and judgement, but it deserves more scrutiny. Paul Craig expands on this, stating two reasons for which Article 50 should be revocable. Primarily, he points out that a party is not bound by a contract or treaty until an agreement has been reached[13]. The government invoking article 50 would do no more than start a process of negotiations and could, theoretically withdraw from negotiations at any point. This idea is affirmed by Article 68 VCLT that provides ‘a notification or instrument provided for in article 65 or 67 may be revoked at any time before it takes effect’[14]. Moreover, Lord Kerr – architect of Article 50 – has demonstrated intention for Article 50 not to be irrevocable in interviews with the media[15]. The ability to revoke Article 50 does not come under sufficient critique in the majority judgement of Miller. The implications of being able to revoke the Article allows sufficient opportunity for parliament to oversee the process. Ultimately, the government’s withdrawal from EU treaties does not force Parliament’s hand as it would subject to substantial review and procedure. It is therefore well within the scope of the Royal Prerogative to invoke article 50 without prior authorisation from parliament.


Restrictions to The Royal Prerogative: 1972 ECA

The judgement of the majority places significant weighting on the 1972 European Communities Act[16], which is said to impliedly restrict the Royal Prerogative by making it unlawful for the executive to take steps which would have ‘the inevitable effect after a period of time, of excluding EU Law.’[17]. The Royal Prerogative’s ability to  enter and withdraw from treaties may be restricted, as is recognized in the constitution as Lord Parmoor said:

‘When the power of the Executive… has been … directly regulated by statute, the Executive no longer derives its authority from the Royal Prerogative of the Crown but from Parliament.’[18]

Therefore, where the 1972 Act provides, the executive must first gain Parliamentary approval before using the Royal Prerogative to withdraw from the EU. This is not the case. Lord Reed expanded on this idea in his dissenting judgement, providing that following the general principles under the Blackburn v Attorey General[19] and Tin Council case[20] there is no legal requirement for the crown, unless provided by statute, to seek Parliamentary authorisation for exercise of its prerogative.

Despite this, there is no statute which excludes the use of prerogative power. The omission of such a clause under the 1972 Act, as it has been argued by Mr Eadie, could imply Parliament had intended to leave this prerogative intact when creating the statute[21]. Contrary to this, it was argued that ‘The fact that a statute says nothing about a particular topic can rarely, if ever, justify inferring a fundamental change in the law’[22]. Car Gardner persuasively contends that this is exactly what the majority judgement had done by reading into the Act a limitation on prerogative powers about which the statute says nothing[23]. It is difficult to justify how the 1972 Act places a limitation on the prerogative powers of the executive. The judgement makes little persuasive argument to establish grounds for which this particular act prohibits the use of the Royal Prerogative, a constitutional right which in the majority Judgement’s own words, infers a fundamental change in the law where it says nothing[24].


The Royal Prerogative is wisely placed in a single hand by the British constitution. If such a duty was subject to many wills, this inevitably promote disunity and create weaknesses in government, as described by Lord Reed[25]. It is therefore paramount that this right remains with the executive and Parliament must only infringe on this where absolutely necessary. The majority judgement given states that a major change to UK constitutional arrangements cannot be achieved by ministers alone using their prerogative, but this is fallacious.  Firstly, the dualist theory of international relations holds that a treaty will only have effect on an international plain unless incorporated into domestic law. The triggering of Article 50 cannot therefore have constitutional implications unless incorporated into statute by Parliament. Secondly, triggering Article 50 would do no more than set in motion a long-winded process subject to substantial consideration and critique from each body of the government. Moreover, there is little to suggest Article 50 could not be revoked once ‘triggered’. Finally, there are no statutory restrictions in place which explicitly imped this right of the executive. And where this has to be inferred, there is surely a violation of the Principle of Legality . Ultimately, the majority judgement in Miller is anything but an ordinary application of the basic concepts of constitutional law when considering its disregard given to the importance and limitations of prerogative powers which rightfully belong to the executive.


[1] K. C. Wheare, Modern Constitutions (2nd edn, Oxford University Press, 1966) 1

[2] AV Dicey, Introduction to the Study of the Law of the Constitution (10th edn, 1959)

[3] AV Dicey, Introduction to the Study of the Law of the Constitution (10th edn, 1959) 424

[4] B.S. Markensinis, The Royal Prerogative Re-visited (vol. 32, No.2, Cambridge Law Journal, 1973) 287-309

[5] R (Miller) v Secretary of State for Exiting the European Union [2016] EWHC 2768 [82]

[6] Lord Templeman in JH Rayner Ltd v Department of Trade and Industry Ltd [1990] 2 AC 418

[7] Jeffrey Goldsworthy, The Sovereignty of Parliament: History and Philosophy (Oxford University Press UK, 1999)

[8] Case of Proclamations [1610] EWHC KB J22

[9] Bill of Rights 1689

[10] R (Miller) v Secretary of State for Exiting the European Union [2016] EWHC 2768 [36]

[11] Alex Peplow, ‘Withdrawal from the ECHR after Miller – A Matter of Prerogative?’ (UK Constitutional Law Association)  <> accessed 10 March 2017

[12] R (Miller) v Secretary of State for Exiting the European Union [2016] EWHC 2768 [94]

[13] Paul Craig, ‘Miller: Winning Battles and Losing Wars’ (Oxford Human Rights Hub)  <> accessed 9 March 2017

[14] Paul Craig, ‘Miller: Winning Battles and Losing Wars’ (Oxford Human Rights Hub)  <> accessed 9 March 2017

[15] Glenn Campbell, ‘Article 50 author Lord Kerr says Brexit not inevitable’ (BBC news, 3rd November 2016) < > accessed 10th March 2017

[16] European Communities Act 1972

[17] David Feldman, ‘Brexit, the Royal Prerogative, and Parliamentary Sovereignty’ (UK Constitutional Law Association) <> Accessed 9 March 2017

[18] Attorney General v De Keyser’s Royal Hotel Ltd [1920] AC 508 (HL)

[19] Blackburn v Attorney General [1971] 1 WLR 1037

[20] JH Rayner (Mincing Lane) Ltd v Department of Trade and Industry [1989] 3 WLR 969

[21] R (Miller) v Secretary of State for Exiting the European Union [2016] EWHC 2768 [37]

[22] R (Miller) v Secretary of State for Exiting the European Union [2016] EWHC 2768 [108]

[23] Carl Gardner: The “principle of legality” is out of control

Carl Gardner, ‘The Principle of Legality is out of control’ (Judicial Power Project) <> Accessed 11 March 2017

[24] R (Miller) v Secretary of State for Exiting the European Union [2016] EWHC 2768 [108]

[25] R (Miller) v Secretary of State for Exiting the European Union [2016] EWHC 2768 [160]

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