Separation of Powers in the UK Constitution

‘Far from being the “efficient secret” of the UK Constitution as Bagehot suggested, the degree of overlap between the legislature and the executive is one of the greatest flaws in the separation of powers in the UK Constitution.’




            The theory of separation of power acts as a fundamental basis for our comprehension of the distribution of power. This is especially the case with regard to the British constitution. According to this doctrine, the power of the government/state ought to be equally divided/dispersed between the three institutions: the legislature, the judiciary, and the executive. In other words, the doctrine demands that the three aforementioned bodies act as separate entities, or expedience various checks and balances with a view to ensuring that one institution does not exercise too much power at the expense of the other two. This, therefore, helps to ensure that there is no abuse of power. An in-depth understanding of the relationships between the legislature, judiciary, and executive is vital for the effective upholding of the rule of law and the constitution. However, these relationships seem to have undergone considerable changes in recent years owing to societal changes and changes in governance.  Montesquieu was instrumental in propagating the idea of separation of powers, but this idea has never really taken root in the UK. However, the notion of fusion of powers is now regarded as a key aspect of the constitution. Walter Bagehot described the close association between the legislative and executive powers of the English Constitution as the 'efficient secret.' Bagehot was referring to the fact that the legislature, and more so the House of Commons, largely forms the executive. In turn, the executive is answerable to the legislature. In the same way, the executive exercises powers over Parliament when it seeks to pass Bills by exercising the prerogative powers of the Prime Minister to call for a general election by dissolving parliament. However, this fusion that Bagehot alluded to is far from efficient. In fact, it is rather flawed as far as the separation of powers between the legislature, executive, and judiciary is concerned, as outlined in the UK Constitution. The premise of this essay, therefore, is to examine these flaws in the degree of overlap between the executive and the legislature, and how this fusion could have had the implication of the separation of power between the three arms of the government.

While the UK lacks a written constitution, it is nonetheless, characterised by a golden rule of separation of powers among the three institutions of the government.  Of the three institutions in the British political system, the main overlap appears to be between the executive and the legislature. Grant describes the “efficient secret” of the UK Constitution as used in reference to the English constitution as the close association between legislative and executive powers.

            There is a good overlap between the executive and the legislature in terms of personnel. For example, the ministers who head the House of Commons are often drawn from Parliament and have the capacity to exercise significant influence over the business affairs of the legislature. This fusion between the legislature and the executive was desirable, according to Bagehot, as it ensured that the government worked efficiently. A delegated legislation is further evidence of overlap between the executive and legislature.  Based on the doctrine of the separation of powers, the legislature is charged with the constitutional role of making laws, while the executive is charged with the role of implementing laws enacted by parliament. The UK Parliament delegates the executive with the legislative powers to enact laws. While this might appear justifiable from a practical context, the separation of powers between the executive and legislature seeks to counterbalance powers between these two institutions.

            By terming the near fusion of the executive and the legislature as 'the efficient secret', Bagehot did not mean to state that this was a secret in the true sense of the word, implying that only a limited number of individuals were aware of it; rather, he meant that such a near fusion was an ingenious way of improving the strength and efficiency of the British Government. While Bagehot's works are still regarded as authoritative more than 150 years later, the setup that he described has however changed since then. For example, the Prime Minister enjoys limited royal prerogative powers largely due to reforms that Gordon Brown initiated in 2007 as Prime Minister. For example, the Prime Minister must first seek consent from Parliament before declaring war on another country. In addition, Parliament now has to review treaties before they can be ratified by the executive, something that was a prerogative power hitherto only enjoyed by the executive. Moreover, the Prime Minister cannot now directly request the Monarch to dissolve parliament without first consulting the House of Commons for approval.   In addition, the enactment of the 2000 Freedom of Information Act has brought about enhanced openness in government. Now, public authorities are compelled to make publish certain information regarding their activities by way of publishing. At the same time, the public has a right to ask for certain information from public authorities.

            The fact that the prime minister and the cabinet who are key members of the Executive are drawn exclusively from Parliament results in the almost total fusion of the legislative and executive powers. Whereas Parliament is mainly charged with the responsibility of enacting legislation, this near fusion of its powers with those of the executive means that its role today is to raise issues regarding the legislation drafted by the executive, which it is expected to approve. Moreover, ministers may also enact delegated legislation. While Parliament is expected to endorse such legislation, the fact that the executive has the power to enact laws further subverts the separation of powers between these two arms of the government and is in itself a symbol of the likely excessive concentration of power. Even as the near fusion of legislature and executive acts as the most potent threat to the 'separation of powers', we also have overlapping functions and personnel that are also worthy of consideration. Already, the 2005 Constitutional Reform Act has removed most of the personnel overlaps between the legislature, the executive, and the judiciary. While this development may appear to have augmented the independence of the judiciary, this is only the case on paper. On the issue of overlapping functions, the executive appears to have total control of Parliament.

The integration of the executive and legislature as provided for by the UK Constitution is believed to offer efficiency and stability to various operations of the government. Ginsburg and Dixon have described it as 'a system that intentionally promotes efficiency over abstract concerns with a threat of tyranny.’ For instance, the fact that the Prime Minister is both the leader of the majority party in Parliament and the head of the executive arm of the government means that the executive exercises more freedom in comparison with the legislature.  In addition, the legislature could delegate the responsibility to enact laws to the executive through what is known as delegated legislation. Consequently, Parliament is spared the responsibility of having to examine small technical details, even as it still preserves Parliamentary consent. This is a further confirmation of the high level of overlap between the UK Parliament and the executive. Conversely, the presence of the Executive in Parliament could aid in the inspection as long as the necessary steps have been implemented. For instance, Parliamentarians could use question time as the opportune time to hold the executive to account.

This notwithstanding, the strong control of the executive over Parliament is quite evident. For example, the fact that the majority party in parliament forms the government means that the government will always enjoy an inbuilt majority and that government bills almost always pass. This also means that because of the dominance of the government in parliament, it, therefore, controls the parliamentary agenda. Parliament also experiences limited opportunities to examine subordinate/delegated legislation developed by the executive through government ministers. The fact that the upper chamber is quite ineffective also leads to weak scrutiny of the Executive.

Additionally, the Salisbury Convention prevents the House of Lords from rejecting bills that make operative noteworthy manifesto obligations of the government. The Official withdrawal of the White Paper for House of Lords reform in September 2012 further spelled doom for the fusion between Parliament and the Executive. Had it been successful, the reform would have strengthened the upper chamber. Even after the executive spearheaded a stripping off of certain prerogative powers of the Prime Minister and ministers, Parliament still struggles in terms of scrutinising the existing Royal Prerogative powers on such sensitive issues as defence, national security, immigration, and deployment of armed forces. This, is even as the 2010 Constitutional Reform and Governance Act has been ratified, which calls for Parliament’s examination of international treaties before they are sanctioned.  On the other hand, there are signs that Parliament is starting to play a key role in regard to exercising the Royal Prerogative. For example, in 2003, Parliament authorised that armed troops be deployed in Iraq, although this was a Royal Prerogative that the Prime Minister was meant to act on. Additionally, Parliament voted in 2013 to decide whether troops should be sent to Syria. Nonetheless, while the government subjected the issue of whether to make a military intervention in Libya to vote in 2011, this did not happen in 2013 when the issue of Mali surfaced.

Barendt summarizes the situation succinctly by contending that in terms of checks and balances, the separation of powers between the executive and the legislature is ineffective. Since Parliament is not in a position to control the executive based on the UK Constitution, this responsibility falls squarely in the hands of the judiciary. Towards this end, the courts have on several occasions made judgements on the ‘separation of powers’ and emphasized that the executive can no longer ignore the Parliament on the matter. For example, in R v Home Dept., the court ruled that even members of the executive ought to abide by the determination of the court. The courts have also indicated that the executive should desist from acting in judicial roles.

In a case where the majority of the seats in the House of Commons are occupied by the government through the executive, the main question that we need to explore is if this acts as an incentive for the government to dominate Parliament and see to it that its proposed legislations have been passed. The other crucial issue worthy of consideration is if sufficient procedures have been implemented to see to it that proposals underwent sufficient scrutiny and that these are either rejected or endorsed. In an attempt to ensure that the executive did not have undue control over the legislature, The 1975 House of Commons Disqualification Act provided the maximum number of salaried ministers allowed for parliamentary sittings in the House of Commons. Besides, Parliament still retains the legislative powers to evict members of the executive arm of the government from office. By seeking to scrutinise ministerial responsibility, Parliament is in effect asking that the executive be accountable to it. However, this is only effective on paper, resulting in mounting complaints regarding the Legislature’s ineffectiveness. The economist has even identified the weakness of parliament and the excessive powers of the executive as the greatest flaw of the UK government system.

The 2011 Parliamentary Voting System and Constituencies Act was yet another opportunity to reduce the powers of the executive over the legislature. With this Act, a decision had been reached that the number of MPs sitting in the House of Commons would be reduced by 50, to 600. The Public Administration Select Committee endevoured to scrutinize the responsibilities and roles of government ministers in a bid to check whether there was an allowance for reductions there as well. Nearly 20% of the MPs in the House of Commons are ministers, having been appointed by the Prime Ministers to head various portfolios. They are thus on the “payroll vote” and as such, are compelled to either vote in support of Government motions or risk losing their ministerial positions. Should the number of MPs be reduced by 50, even as the number of government ministers remains static, there would be a resultant rise in payroll vote. Consequently, the executive would become even more powerful in comparison with Parliament.  Under s14 of the 2011 Parliamentary Voting System and Constituencies Act, there is a need for a review of the impact of reducing the number of MPs in the House of Commons by 50. 

Another area in which the executive arm of the government exerts control over the legislature is with respect to the time allocated for debates on the floor of the house. It is important to note that the Government often has nearly full control over legislative debates.  Consequently, in 2010, the Backbench Business Committee was established with a view to giving Parliament increased operational independence over the executive. In making this recommendation, the Wright Committee was convinced that creating the Backbench Business Committee would grant MPs increased ownership and control over the legislative agenda, augment the review function of Select Committees, and ensure that the public found Parliamentary debates more relevant. More importantly, MPs would be in a position to apply for additional time on the floor of the house courtesy of the Backbench Business Committee.


The “efficient secret” of the UK Constitution that Bagehot had in mind, is laden with flaws as far as the separation of powers between the executive and the legislature is concerned. The high level of overlap between these two arms of the government is meant to balance power so that none of them abuse its powers. In others words, the move was intended to institute a checks and balances system. Parliament would scrutinise the activities of the executive and the government through the executive would also examine the activities of MPs. However, the reality is that the executive appears to have a lot of powers when compared to Parliament. For example, the decision to reduce the number of MPs in the House of Commons by 50 even as the number of ministers remains static, is telling. Moreover, ministers are on the Government’s “payroll vote” and as such, have to support its bills in Parliament or resign.  Furthermore, Parliament has no control over certain Prerogative Powers such as those concerned with the decision to declare war on another country, although it did vote on the decision to deploy armed forces into Iraq.  This is a clear indication of the weakness of the legislature relative to the exercise of powers enjoyed by the executive, culminating in the greatest flaw in the UK Constitution.






Bagehot W, The English Constitution (Chapman and Hall 1867) 37

Bradley, E, Constitutional and Administrative Law (15th edn, Longman, 2011) 69

Doherty, M, Public Law (Taylor & Francis 2016) 67

Galligan B and Brenton S, Constitutional Conventions in Westminster Systems (Cambridge University Press 2015) 180

Gibson, B, The New Ministry of Justice: An Introduction (Waterside Press 2008) 148

Ginsburg T and Dixon R, Comparative Constitutional Law (Edward Elgar Publishing 2011) 248

Grant, M, Key Ideas in Politics (Nelson Thornes 2003) p. 133 

Kavanagh D and Cowley P, The British General Election of 2010 (Palgrave Macmillan 2010) 71

Pollard, D, Parpworth, N and Hughes, D, Constitutional and Administrative Law: Text with Materials (OUP 2007) 46

Smartt U, Optimize Public Law (Routledge 2014) 94

Tomkins, A, Public Law (OUP 2003) 106

Turpin C and Tomkins A, British Government and the Constitution: Text and Materials

(Cambridge University Press 2007) 113.

Article journals

Barendt E, 'Separation of Powers and Constitutional Government' [1995] Winter Public Law 599. 57

Jowell J,’ Parliamentary sovereignty under the New Constitutional Hypothesis’ [2006] Public Law 562

Woodhouse D,’ Independence the English way’ 5 (2007) ICON 153.


Constitutional Reform Act 2005

Constitutional Reform and Governance Act 2010

The House of Commons Disqualification Act 1975

Parliamentary Voting System and Constituencies Act 2011

Case Laws

R (Anderson) v Secretary of State for the Home Department [2003] 1 AC 837

R v Secretary of State for the Home Department, ex parte Northumbria Police Authority [1989] 1 QB 26 

Online Articles

House of Commons Reform Committee,’ Rebuilding the House: First Report of Session 2008-09, HC 1117, November 2009, section 181’

Kelly S,’ The slow death of the ‘Efficient Secret’: The rise of MP independence, its causes and its implications’ (2014)

Public Administration Committee, ’Smaller Governments: What do Ministers Do?’ (2011)

The Economist,’ The coronation’ (2007)



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