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Respect and Co-operation: Building a Stronger Union for the 21st century Contents

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Chapter 3: Parliamentary sovereignty

77.We have said “Parliamentary sovereignty is the defining principle of the United Kingdom’s constitution. By this principle, Parliament’s law-making power is not subject to any permanent restrictions and therefore Parliament cannot bind its successors.”95 While Parliament can choose to place limits on the exercise of its sovereignty, as it did by enacting the European Communities Act 1972, it can also remove these, as it did by repealing the 1972 Act almost half a century later.

78.It has remained the accepted view that Parliament has “the right to make or unmake any law whatever”. This is expressly reiterated in the devolution statutes.96 For example, section 28(7) of the Scotland Act 1998 states: “This section [which provides for the legislative competence of the Scottish Parliament] does not affect the power of the United Kingdom to make laws for Scotland.” Parliament clearly intended that its sovereignty should be unaffected by the devolution statutes. The Scotland’s Parliament White Paper said: “the UK Parliament is, and will remain, sovereign in all matters”, and “Westminster will be choosing to exercise that sovereignty by devolving legislative responsibilities to a Scottish Parliament without in any way diminishing its own powers.”97

79.This position has been frequently restated by the courts in judgments concerning devolution matters. In the AXA case, Lord Hope of Craighead98 said: “[a] sovereign Parliament is, according to the traditional view, immune from judicial scrutiny because it is protected by the principle of sovereignty”.99 In the 2018 Continuity Bill Reference the Supreme Court referred to section 28(7) as representing “the continued recognition of [Parliament’s] unqualified sovereignty”.100 In October 2021 the Supreme Court used section 28(7) to draw a clear distinction between the sovereignty of the UK Parliament and the limited authority of the Scottish Parliament. The Scottish Parliament “has plenary powers within the limits of its legislative competence. But it does not enjoy the sovereignty of the Crown in Parliament … Parliament … has an unlimited power to make laws for Scotland, a power which the legislation of the Scottish Parliament cannot affect.”101

80.However, devolution precipitated the adoption of a self-denying ordinance by the UK Parliament. During consideration of the Scotland Bill by the House of Lords in October 1998, Lord Sewel, then Parliamentary Under-Secretary of State at the Scottish Office, said:

“Clause 27 [which became section 28] makes it clear that the devolution of legislative competence to the Scottish Parliament does not affect the ability of Westminster to legislate for Scotland even in relation to devolved matters. Indeed … we envisage that there could be instances where it would be more convenient for legislation in regard to devolved matters to be passed by the United Kingdom Parliament. However, as happened in Northern Ireland earlier in the century, we would expect a convention to be established that Westminster would not normally legislate with regard to devolved matters in Scotland without the consent of the Scottish Parliament.”102

81.What became known as the ‘Sewel convention’ was articulated in a Memorandum of Understanding between the UK Government and the devolved administrations:

“The UK Government will proceed in accordance with the convention that the UK Parliament would not normally legislate with regard to devolved matters except with the agreement of the devolved legislature. The devolved administrations will be responsible for seeking such agreement as may be required for this purpose on an approach from the UK Government.”103

82.In relation to the Senedd and Scottish Parliament this convention has been given statutory recognition.104 This however did not change its nature as a political constraint on Parliament, lacking legally enforceable authority.105 The Sewel convention was addressed by the Supreme Court in the first Miller case, concerning the UK’s withdrawal from the EU.106 The court stated: “While the UK government and the devolved executives have agreed the mechanisms for implementing the convention in the Memorandum of Understanding, the convention operates as a political restriction on the activity of the UK Parliament.”107 The court confirmed that the convention was not justiciable, saying: “Judges … are neither the parents nor the guardians of political conventions; they are merely observers.”108 The court confirmed that section 28(8) of the Scotland Act was “not seeking to convert the Sewel convention into a rule which can be interpreted, let alone enforced, by the courts; rather, it is recognising the convention for what it is, namely a political convention.”109 We consider the operation of the Sewel convention in the next chapter.

83.Professor Michael Keating, Chair in Scottish Politics at the University of Aberdeen, told us:

“There are two interpretations of the devolution settlement. One is based on the traditional doctrine of parliamentary sovereignty and suggests that Westminster has merely lent powers to the three devolved territories, which can be reclaimed at any time. The other is that devolution represents a substantial constitutional change and requires a modification of our understandings of parliamentary sovereignty and supremacy. The former view has been generally sustained by the courts, including the Supreme Court. The latter has been expressed by many academic commentators as well as by some judges in writings, lectures and obiter dicta.”110

84.The Scotland Act 1998 and the Government of Wales Act 2006 have each been amended to guarantee the permanence of the devolved institutions, stipulating they can only be abolished with the consent of the voters in Scotland and Wales,111 with no suggestion that the creation of devolved institutions or the conferral of powers on them is in any way temporary.112 Furthermore, the authority to make law has been given by Parliament to the devolved legislatures and subsequently extended at regular intervals.113 While parliamentary sovereignty means the UK Parliament could, theoretically, abolish the Senedd and the Scottish Parliament it is extremely unlikely to do so, without consent, due to the significant political and constitutional consequences this would have.114 Furthermore, while the permanency provisions may not be intended to be enforced by the courts they can provide evidence of constitutional significance, therefore guiding the conduct of government and acting as an aid to political scrutiny.115 Although the Parliament of Northern Ireland was abolished in 1973, this enjoyed cross-party support at Westminster given the circumstances which were generally acknowledged as exceptional.

85.The Supreme Court has been at pains to point out no modification of Parliament’s legal supremacy has taken place. Any suggestion that Parliament’s legislative supremacy is even open to modification is rare and speculative.116 Even those who would favour a different constitutional ordering for the UK recognise the nature of Parliament’s supremacy. Angus Robertson, in evidence to the Committee, acknowledged that parliamentary sovereignty was the current constitutional reality in the UK.117

86.In recent times the Supreme Court, when deciding cases on devolution issues, has consistently reaffirmed that parliamentary sovereignty remains a fundamental doctrine of our constitution. We welcome this legal clarity, while recognising that how Parliament chooses to exercise this sovereignty is subject to substantial political constraints.

Political conceptions of sovereignty

87.Parliament’s sovereignty, manifest in the power to make or unmake any law, can be expressed as the legislative supremacy of Parliament. However, we heard that sovereignty has a political as well as a legal dimension: that Parliament’s legal authority rests on, and its exercise is conditioned by, political legitimacy.

88.Some witnesses believed that devolution had changed the political underpinnings of parliamentary sovereignty. The origins of devolution, legitimised as they were in the three devolved territories by referendums, give rise to claims that popular sovereignty stems from different democratic mandates in Scotland and Wales and Northern Ireland. We heard that, as a consequence, sovereignty should be considered as ‘shared’ across the UK and that the doctrine of parliamentary sovereignty should be updated to reflect this.118

89.It seemed clear that some witnesses were referring to the political rather than legal dimension of sovereignty, but they did not always clearly distinguish between these two aspects.

90.The Welsh Government has said:

“Whatever its historical origins, the United Kingdom is best seen now as a voluntary association of nations taking the form of a multi-national state, whose members share and redistribute resources and risks amongst themselves to advance their common interests. Wales is committed to this association, which must be based on the recognition of popular sovereignty in each part of the UK; Parliamentary sovereignty as traditionally understood no longer provides a sound foundation for this evolving constitution.”119

91.The Scottish Government has said:

“The permanence of devolution in the UK’s constitutional arrangements [needs] to be recognised, with justiciable protections in law for the powers of the devolved institutions, as is the case in other states. A new legal framework should create these protections, and incentives to resolve any issues by agreement rather than by imposition from Westminster.”120

92.It is well-recognised that the UK is a union of nations, a fact observed by the Committee.121 It is also clear that the idea of popular sovereignty has been widely recognised as the political principle underpinning the legitimacy of parliamentary sovereignty. A.V. Dicey advanced this idea in discussing the role of constitutional conventions which “give effect to the will of that power which … is the true political sovereign of the state—the majority of the electors”.122 Dicey divided the attributes of sovereignty between, on the one hand, the legal sovereign: “the person or body with the power of law-making unrestricted by any legal limit”; and, on the other, the political sovereign: the person or body whose will “is ultimately obeyed by the citizens of the state”.123 It is therefore long understood in the UK’s constitution that Parliament’s legal sovereignty rests for its validation on the will of the people, as expressed through UK general elections.

93.In our report The Union and Devolution we were clear that Parliament has been responsive to the aspirations of the devolved territories for further powers: “successive Governments have responded individually to demands from each nation. Devolution has thus developed in an ad hoc fashion, with different constitutional conversations taking place separately in different parts of the country.”124 On that basis it is difficult to see why parliamentary sovereignty “no longer provides a sound foundation for this evolving constitution”. Arguably it has been too responsive to demands for an ‘evolving constitution’ at the expense of a more strategic approach to constitutional change that promotes the Union as much as it furthers devolution.

94.Some witnesses focused not so much on the reality of Parliament’s supremacy but on how that supremacy was being used by the Government, in their view on occasion illegitimately. As we discussed in the previous Chapter, the Brexit process was a particular point of focus, with the UK Government said to be conducting an “executive power grab”.125

95.There might appear to be a difference between the doctrine of parliamentary sovereignty as reflected in legislative supremacy and the rather more elusive concept of popular sovereignty. We are not convinced that there is much practical distinction between them. The UK Parliament’s legislative supremacy ultimately depends for its political legitimacy on the consent of the people, as expressed in UK general elections.

96.The UK Parliament has legislated to devolve power and has established in statute the devolved institutions. In theory, it could legislate to abolish them. In reality, it would not do so, and certainly not without the express consent of relevant voters in a referendum, as recognised in the devolution statutes. This is an illustration of the existence of the political constraints which in practice circumscribe the legislative supremacy of the UK Parliament.

97.Parliamentary sovereignty has operated for centuries subject to such constraints. Parliament is also not the only source of law within the constitution: the Royal prerogative and the common law represent distinct areas of lawful authority and set important practical limitations upon Parliament’s legislative reach, as do the United Kingdom’s increasing international obligations.

98.Constitutional conventions also circumscribe Parliament’s law-making capacity if not its formal competence. In the context of devolution, the Sewel convention provides a specific restraint on the UK Parliament’s power to legislate in devolved areas, which is also explicitly recognised in statute. We discuss in the following chapter the effectiveness of the convention. As with other checks and balances and political constraints, there may, from time to time, be tensions in the operation of the convention. However, we consider that the doctrine of parliamentary sovereignty has successfully accommodated the process of devolution and will continue to do so. Parliament’s legislative authority must continue to be exercised with respect and restraint if the Union is to be strengthened.

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