The illusions of parliamentary sovereignty

A picture of the UK Parliament under a blue sky. This images is used to illustrate an article about parliamentary sovereignty.

Gareth S. Williams, Chair of the Expert Panel to the Independent Commission on the Constitutional Future of Wales, unpacks the history of parliamentary sovereignty in UK institutions.

This month (January) sees the publication of the Final Report of the Independent Commission on the Constitutional Future of Wales.

The report will give an account of the national conversation around our constitutional future, which the Commission has stimulated. But more importantly, it will also provide an objective analysis of the different options potentially available to Wales which is intended to generate and inform increased discussion of what constitutional arrangements might best secure the future prosperity and well-being of the citizens of Wales. 

The publication of the Commission’s report follows on the heels of two other reports which may well have a key role to play in informing the constitutional choices of any new government after the next General Election. Firstly, the report of the Labour Party’s Commission on the UK’s Future, led by Gordon Brown – published in December 2022 and endorsed in its entirety by Labour leader Keir Starmer. This  argues that the further decentralisation of political power is a necessary condition for UK economic success. 

And secondly, the final report of the Review of the UK Constitution undertaken by the Institute for Government and the Bennett Institute for Public Policy in September 2023, whose lead co-author, Jess Sergeant, has just been appointed as Director of Constitutional Change for Labour Together

Over the last 150 years, Parliamentary sovereignty has ceased to be a check on the executive, and has rather become a weapon of centralising power in the hands of the executive.

While both reports contain many sensible recommendations for an incoming Government, both – highly regrettably in my view – continue to stress parliamentary sovereignty, the freedom of Parliament to legislate in whatever way it sees fit, as a necessary cornerstone of the UK’s famously unwritten constitution. Thus the Brown report talks of the need to ‘sustain the principle, at the core of much of the UK constitution of Parliamentary supremacy’ (p.40) while the Bennett Institute and Institute for Government Review states baldly that ‘Parliament’s sovereignty is the UK’s central constitutional principle’ and warns that ‘moving away from a system based on parliamentary sovereignty, developed over many centuries….would be a major undertaking’ (p.23).

However, I would contend that relying on parliamentary sovereignty as a guiding principle of our constitutional future is misguided, even reckless. This is for both theoretical and practical reasons. 

A history of Parliamentary Sovereignty in the UK 

The concept of parliamentary sovereignty has been warped out of all recognition since it was first mooted in the 17th Century.

Parliamentary sovereignty was conceived – and until the early 20th century functioned – as a system of checks and balances between the three essential parts of the ‘Crown in Parliament’: the King, the House of Lords and the House of Commons. It was coined at a time when the Crown itself wielded executive power, limited only by Parliament’s powers over taxation and legislation as set out by the 1689 Bill of Rights. Ministers were appointed by and answerable to the monarch and the view that a ‘Prime Minister’ – a term unknown except as an insult until the 19th Century – and the government needed to command a majority in Parliament only developed gradually over the course of nearly 200 years. By ensuring that the agreement of all three institutions was needed to legislate or to provide funds to the executive, the purpose of parliamentary sovereignty was to restrain it.

Parliamentary sovereignty in the eighteenth and nineteenth century was also used as an argument against the revolutionary doctrine of popular sovereignty as championed by the American and French Revolutions, perhaps most notably by Edmund Burke. We should bear this in mind given that the sovereignty of the people has been a fundamental tenet of democracy from ancient Athens onwards.

Syniadau uchelgeisiol, awdurdodol a mentrus.
Ymunwch â ni i gyfrannu at wneud Cymru gwell.

Over the last 150 years, Parliamentary sovereignty has ceased to be a check on the executive, and has rather become a weapon of centralising power in the hands of the executive. In practice, the effectiveness of the threat of a monarch refusing to sign legislation has gradually waned, to the point it is now completely ineffective. In addition, the Salisbury Convention, and the fact that at the end of the day the executive can appoint whoever it wants to the House of Lords, means that while the Lords of course fulfils many essential functions it cannot withstand the will of the Commons (except in any amendment to the length of the Parliamentary term). And finally, as we have seen (and not just in the last three years, but under the Thatcher and Blair Governments) in all but the most exceptional circumstances, a government (executive) with a large majority can push through whatever legislation it chooses, using not only party discipline, but also patronage through the use of the honours system, for example. 

The limits of Parliamentary Sovereignty

In short, the whole idea of parliamentary sovereignty in the 21st century has become corrupted from its origin as a way of keeping the executive in check, to a tool allowing the executive to wield more or less absolute power. And with the current First Past the Post electoral system, the power of the executive does not depend on persuading more than a significant minority of the electorate to support it. 

It is the fact that the UK Government can use Parliament to get its way that allows it to behave as if the Welsh and Scottish Governments and the Northern Ireland Executive are subordinate.

In practice, what we have seen over the last century is parliamentary sovereignty being used as an argument for allowing the government of the day to do whatever it likes. In Westminster, and amongst all political parties, this has resulted in a culture of believing that all political authority must flow from Parliament i.e. the government. This manifests itself in the lack of any constitutional basis for local government and the practical emasculation of its capacity to finance itself. It is also evident in the way the UK Government refuses to acknowledge the equal legitimacy of devolved administrations, despite the fact that, in theory, the supremacy of Parliament over devolved legislatures is not mirrored by the same relationship between governments – it is the fact that the UK Government can use Parliament to get its way that allows it to behave as if the Welsh and Scottish Governments and the Northern Ireland Executive are subordinate. Over recent decades, the corruption of parliamentary sovereignty has also become clear in the hostility to the EU, and even now organisations like the Council of Europe and the European Court of Human Rights, which have any power to hold it in check.

So, while the report co-authored by the Bennett Institute and the Institute for Government makes many sensible recommendations, it is flawed (possibly fatally) by basing them around continued Parliamentary sovereignty. In particular, it requires Parliament (and more specifically the House of Commons) to put in place and then continue to respect a series of procedures constraining the freedom of the Parliamentary majority to act as it sees fit with regard to constitutional matters – and in particular the powers of the devolved institutions –  without any formal check on it from doing so. This is unlikely to survive the first contact with reality. 

The Brown Commission makes a good attempt to re-invent Parliamentary sovereignty as a system of internal checks and balances once more, with proposals for House of Lords reform which would give the new second chamber a veto over proposed changes to core constitutional statutes. But since this again relies on the Commons voting to curb its own supremacy, it is surely questionable whether it will actually happen. It would be more honest to call time on the whole concept.

What is the alternative?

Both of these reports are wary of opening what they see as a pandora’s box by trying to develop a written constitution. But while undoubtedly a UK ‘national conversation’ about developing a written constitution based on popular sovereignty would be challenging (though I would argue also cathartic), there are some indications that (as with electoral reform) the general public are more open to this than the political elite. 

Syniadau uchelgeisiol, awdurdodol a mentrus.
Ymunwch â ni i gyfrannu at wneud Cymru gwell.

The polling for the Brown Commission (which is available independently of the Commission’s own analysis) shows that when asked to choose between the statements ‘we need radical change in how political power and public money are distributed in Britain’ and ‘any change we make to Britain’s political system should be careful and gradual’ , 57% of all respondents opted for the former and only 31% for the latter. All age groups and other sub-groups showed broadly the same pattern with the exception of those aged 75 and above (who favoured gradualism by 52% to 44%) and 18 – 24 year olds who were evenly split at 40% for each of the two statements (with a much higher level of ‘don’t knows’ 21% than in other groups). 

Similarly, polling under the State of the Union project produced by the Wales Governance Centre, Cardiff University and the University of Edinburgh, and commissioned by the Independent Commission on the Constitution of Wales, suggested that there a plurality of voters in all four parts of the UK who support the concept of a written constitution: 41% of the samples (including don’t knows) in England and in Wales, 42% in Scotland and 46% in Northern Ireland. This was a finding which surprised the authors of the report.

So surely now is the time to recognise that parliamentary sovereignty is a fallacy which stands in the way of developing a modern constitution – a constitution rooted in popular sovereignty, which puts in place robust checks and balances; a constitution based on a model of distributed power, where the legitimate role of the devolved parliaments and governments, local government and, indeed, international institutions to exercise power is recognised and celebrated.


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Gareth S. Williams is a Former Special Adviser in the Welsh Government (2016 – 2021), and Chair of the Expert Panel to the Independent Commission on the Constitutional Future of Wales. This paper is written in a personal capacity.

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