Unclear constitutional rules add to the immediate uncertainty of a hung parliament  

Constitutional practice is clear when it comes to majorities. A prime minister who wins an election is asked to form a government and immediately they have full powers and legitimacy.

But when it comes to hung parliaments the process is complex. Given how constitutional conventions have been pushed to their limits in the last year, an unclear election result could trigger a period of real uncertainty over who should run the country.

If there is no majority government, then the incumbent PM can hold on to power

When UK general elections fail to produce a clear majority, incumbent prime ministers have an advantage – no new government can be formed until their resignation. The incumbent PM can negotiate with other parties in an attempt to win their support, or they can fight on as head of a minority government.

If the election results in a hung parliament, then Boris Johnson will have to decide whether he has the numbers to stay on in office. He may focus on whether he thinks he can get his Brexit deal passed by Parliament. If the numbers look narrow, and if Johnson faces pressure to accept a referendum, then he may well immediately resign and let Jeremy Corbyn take on the referendum challenge.

But it also matters what the other parties do – and what the numbers allow them to do. In the hours and days after any hung parliament election result, opposition parties may go into negotiations – as we saw in 2010 when the Lib Dems and Conservatives took five days to forge a deal. If a combination of opposition parties can demonstrate a clear majority – whether through a coalition or confidence and supply agreement – then this puts immediate pressure on the incumbent to resign. In February 1974 and May 2010, the incumbent PM resigned when they clearly didn’t have the support of enough MPs, even though the leader of the opposition was also unable to command a majority. In both cases they resigned in favour of the party with the highest seat share.

If an incumbent PM tries to govern as a minority, then they must win the confidence of MPs

The constitution allows incumbent prime ministers to continue in office until they have been shown not to have the support of the Commons. Just like Stanley Baldwin in 1923–4, Boris Johnson could decide to stay on and ‘test the will of the House’.

The test has historically been the votes on the Queen’s or King’s Speech, which play a symbolic constitutional role in demonstrating that a government has support for its legislative plans. A Queen’s Speech is planned for 19 December. But there are usually five to six days of debate before it is voted on – and there is no date set for this vote. The Christmas break means several weeks could pass before we know whether Johnson’s government will survive or when the opposition can try to govern instead as a minority.

A further complication could arise in this scenario if Johnson decided to stall the Queen’s Speech vote, as he did in October, in order to force a vote on his Withdrawal Agreement first. Does this vote then become the new way of testing the House? Again, there could be several weeks before this becomes clear.

The Fixed-term Parliaments Act complicates how a minority government establishes confidence

In the world of highly unlikely, but theoretically possible, constitutional election scenarios, perhaps the most controversial would be the possibility of a government refusing to resign after losing a Queen’s Speech vote – and daring the opposition to use the Fixed-term Parliaments Act to force it from office.

If the opposition had to bring a vote of no confidence under the FTPA, and if the government lost this vote, then this would trigger a 14-day period – as set out in the legislation – in which a government needs to pass a vote of confidence. Failure to do so – and not allowing the chance for the opposition to attempt to form an alternative government – would mean another general election. This outcome would seem to make it an unthinkable option.

The parties could manage without the FTPA – which would be sensible given they both want to abolish this legislation. If either the government or opposition wanted to use votes in the House to test confidence formally, then they could instead use a vote on the Queen’s Speech, a de facto test like a vote on the second reading of the Withdrawal Agreement Bill, or a vote of confidence worded differently to that set out in the FTPA. All they have to do is abide by the principle that you govern on the basis of the confidence of the House. The FTPA route should only be used if parties actually wanted to trigger a general election only weeks after the previous one has taken place.

Restrictions apply to governments after an unclear election result – but it is not clear for how long

The final constitutional problem centres on the level of restrictions placed on the incumbent government while the question of its ability to govern is being established.

The Cabinet Manual sets out how some of the restrictions that apply during the election period would continue to apply following an unclear election result. In the five days after the May 2010 election, with coalition negotiations ongoing, Labour’s Chancellor Alistair Darling travelled to Brussels to negotiate a euro stabilisation fund in the midst of the Greek financial crisis. He did so according to the convention that such ‘essential business’ required ministers to consult with the opposition, and informed George Osborne, the Conservative shadow chancellor, albeit not giving Osborne any say in the negotiations.

While these restrictions exist and have been used before after a hung parliament result, it is difficult to say how long they should last and what signifies their end. Winning a Queen’s Speech might perform this role, but this might not take place for a number of weeks. Until then a government might be unable to announce new policy, make public appointments, award contracts, or start new communication campaigns. It is hard to imagine any government wanting to operate for long with those restrictions.

But the Cabinet Manual provides no guidance how long restrictions should last. Part of the reason is probably that the authors wanted to avoid restricting a minority government which is only a few seats short of a majority. But in a scenario where there is not only lack of clarity about who can command confidence, but also dispute about how, the lack of more specific caretaker rules starts to become a problem.

None of these scenarios will come to pass if the election results in a majority government. But the fact that they need to be discussed – and that there are so many potential pitfalls to think through – suggests that government formation is yet another area of our constitution that needs addressing after this election.

An unclear election result naturally triggers a period of uncertainty. It is not helpful that our current constitutional arrangements muddy the waters still further.