The day after the dramatic ruling of the UK Supreme Court that the prime minister could not ask the Queen to “prorogue” (ie suspend) parliament for as long as he liked whenever he liked, a newspaper columnist wrote a piece headlined “Britain has become a Republic with [House Speaker] Bercow at its head”.


Needless to say, the readers of the piece were not expected to approve of this development. But raising the question of whether the UK is, in effect, a constitutional republic with the House of Commons at its head highlights some of the ways in which the British and American constitutional orders have diverged – even while sharing common assumptions and histories.

At the heart of the American constitutional founding is an irony: although they railed against the overbearing executive power of the British monarch, they ended up creating an executive presidency with far more power than the king or queen of England was ever to have again. The US Constitution most closely resembles the British constitution of the early 17th century before parliament started asserting its sovereignty – a process that has continued right up to the Supreme Court’s decision on proroguing.

Britain's House of Commons
Britain's House of Commons in session, April 1986. Since the beginning of the 20th century prime ministers have almost always been MPs rather than Lords, since the Commons is by far the more important chamber. (Photo by Bettmann via Getty Images)

Republic v monarchy

The US is a republic with the form of a monarchy, while the UK is a monarchy with the form of a republic – and, to a greater or lesser extent, this has been true ever since the American Revolution.

The US has a chief executive who combines being head of government (the initiating and implementing policy bit) and head of state (the formal, ceremonial bit). A president has a similar constitutional function to that pre-18th century English kings – needing congressional (or parliamentary) approval for tax and spend, but with huge prerogative powers. Of course the American president, unlike the British monarch, is elected, and since 1796 has been elected in nationwide and often polarising contests – yet once in office they have the power and many of the trappings of an early modern monarch.

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In the UK, by contrast, the formal executive is split. The head of state (the Queen) is unelected but supposed to have no political role at all, while the head of government (the prime minister) is in office not because the Queen wants them there but solely because he (or she) commands a majority in parliament.

Separation of powers

In the US, the principle of the separation of powers means that the executive branch – the president and cabinet – cannot also be members of the legislature. Nor can they be members of the judicial branch. In the UK all these functions are not only mixed up, they are inter-dependent. The prime minister and cabinet have to be members of either the House of Commons or the House of Lords (the appointed upper house). Since the beginning of the 20th century prime ministers have almost always been MPs rather than Lords, since the Commons is by far the more important chamber. In 1963, parliament passed the Peerage Act allowing hereditary peers (i.e. Lords) to renounce their titles on accession.

Up until recently, the highest court of appeal was the House of Lords, though in practice only its judicial members heard cases. Since 2009 the judicial function of the House of Lords has been handed to a Supreme Court and Justices are directly appointed to the Supreme Court on the recommendation of a selection commission.

The Lords Chamber
The Lords Chamber, the most lavishly decorated room in the Palace of Westminster. (Photo by Arcaid/Universal Images Group via Getty Images)

How much power does the British queen or king hold?

Up until the beginning of the 19th century, monarchs played an active role in the choice of their prime minister and cabinet and various corrupt strategies were used to ensure that, once in office, the prime minister would be able to get bills passed through the legislature. But for the last two centuries and more, the process has flowed exclusively the other way: whatever their personal views may be, the monarch has no choice but to invite whoever can command a majority in the House to form a government.

The bottom line is that the prime minister does not derive his or her authority from their party members or from the relatively tiny number of people who voted for him or her into parliament (he or she is, after all, only one of 650 MPs) but from the House of Commons. The moment he or she loses the “confidence” (ie the support) of the House, the convention has always been that they would resign and invite the Queen to either appoint an alternative prime minister or call a general election.

The prime minister and the confidence of the House

Britain is now in the midst of a greater constitutional crisis than at any time since at least the Edwardian period. At the heart of the current crisis is not Brexit per se but a constitutional system that is breaking down because the link between the prime minister and the legislature is no longer clear. Boris Johnson became prime minister after the resignation of Theresa May because the Conservative Party membership elected him leader and the Conservatives were the largest single party (though without an overall majority) in the House of Commons.

At the time of writing, the Johnson government has not yet faced a formal vote of confidence; so it has not yet been formally established whether he has the support of a majority of MPs. The fact that his government has lost vote after vote in the Commons, including on its central Brexit policy, suggests that it does not.

So the government remains in office but not in power. It can’t pass any legislation, not even the legislation it would need to call an early general election. This is an unprecedented situation in British history. The old remedies now can’t be used – the prime minister can’t just ask the Queen for a dissolution and a general election because of the Fixed Term Parliament Act, passed in 2011 which gave to parliament the royal prerogative power of dissolving parliament which previously had been exercised solely by the prime minister, theoretically on behalf of the monarch.

The opposition don’t want to call a vote of no confidence immediately, or support a general election, because of the peculiar circumstances of Britain’s highly fraught attempt to leave the EU. If there is no withdrawal agreement in place by the deadline of 31 October, Britain would “crash out” with devastating consequences (at least in the view of many commentators). If an election happened right now, there would be no way to prevent that outcome, thus prejudging the decision of the electorate on the most consequential issue in modern British history.

No previous British prime minister has as little formal power as Boris Johnson now has

So, we have an impasse of a kind that is not supposed to happen in the UK parliamentary system in which the executive (the prime minister and his or her government) are at odds with the legislature (the House of Commons). Supporters of the government claim that parliament is “frustrating the will of the people” as expressed in the referendum of 2016, in which a slim majority voted to leave the EU. But to any previous generation, the notion that parliament could be frustrating the will of the people would have been an oxymoron – since “the people” have no singular voice in a plural nation; parliament – the place to speak, to debate, to “parley” – is their forum. You can use referendums to provide legitimacy to decisions, or you can have a parliament that makes decisions on behalf of the people who elected it. But you can’t really have both because they are contradictory, not complementary, ways of determining popular legitimacy for a policy course.

The promise of those campaigning to leave the EU in the 2016 referendum was that leaving would restore parliamentary sovereignty. It appears to have done that even before the UK has left, though not, as the Brexiteers thought, through the repatriation of powers from the European Commission in Brussels, but by taking them from the executive. No previous British prime minister has as little formal power as Boris Johnson now has. Previous parliaments have already effectively claimed the right to determine the decision to go to war and when to call an early general election. Now parliament has been assured, by the Supreme Court, of the right not to be dissolved against its will.

The growth of American executive power

But while the executive in Britain has diminished in relation to the legislature, in the US executive power has grown over many decades. The US president is immune from prosecution while in office – the privilege of monarchs through the ages. Some legal theorists in the US think the president (whoever he or she is) should exert even more power than he or she already does.

In the 17th and 18th centuries, British and American polities struggled with how to contain arbitrary executive power. The Americans thought they’d come up with the answer by separating the executive from the legislature. The British pursued an alternative strategy of making the executive dependent for his or her authority on the legislature. Both approaches have provided mostly stable government (with some dramatic exceptions) for over two centuries. Both now are undergoing a fiery trial that raises profound questions about their design.


Adam I P Smith is the Edward Orsborn Professor of United States politics and political history at the University of Oxford and the Director of the Rothermere American Institute. He also regularly writes and presents documentaries for the BBC. His latest book is The Stormy Present: Conservatism and the Problem of Slavery in Northern Politics, 1846–1865 (The University of North Carolina Press, 2017). To find out more, visit