Referendums, as the British are increasingly aware, are different from general elections. In the latter a party makes a series of promises they then attempt to implement in office. This is their electoral mandate. If the electorate don’t like how these turn out, they kick them out. In contrast, however illusory, contradictory or empty the promises made by the winning side in 2016 may have proved in practice, there is no ready-made constitutional mechanism for a re-think a few years after a referendum.
Of course, as the Royal Commission on Electoral Systems pointed out back in 1910, in effect a general election is itself a referendum. It reduces a complex series of public policy choices to the simple question: do you want this party or that to govern for the next five years? The 2016 referendum is analogous only in the sense that it reduced a complex series of issues - many of which had little or nothing to do with the EU - to a simple question of leaving or remaining.
The key difference is that following a general election the winning party’s manifesto at least indicates how they might address the complex issues the electorate has authorised them to manage. Referendums have no equivalent. There is no constitutional requirement for the winning side to come up with something like a manifesto, setting out how they intend to implement the result, though in future there probably should be. The result is that while the 2016 referendum narrowly gave a mandate for Brexit, it certainly did not give a mandate for any particular model.
Since then the electorate has conspicuously refused to endorse the particular, if vague, model that Theresa May put to them in the 2017 general election. In consequence, although there may be a mandate for leaving the EU it is much less clear that there is a mandate for the current government’s plans for doing so.
From here several scenarios can be sketched out. The first, which seems to be believed by surprising numbers of Remainers, can rapidly be disposed of. This is that somehow the difficulties and economic pain of Brexit will become so obvious that even the May government will drop it. Quite apart from the internal warfare in the Conservative party that such a decision would cause, there is no democratic mandate for it. Clearly then this is not going to happen.
The second, more plausible, scenario involves the House of Lords. As the government does not have a mandate for its version of Brexit, the 1945 Salisbury convention, whereby the Lords have to respect the programme of a majority government, does not apply. Peers could therefore clearly mangle legislation as long as they concentrate on the manner of leaving the EU, rather than the principle of doing so. Whether they choose to do so remains to be seen. If they do so the present constitutional morass will further deepen. For the government has been foolish enough to hold a parliamentary session which lasts two years. They have thus hamstrung their ability to use the 1949 Parliament Act procedure, whereby they can only override the upper chamber if it has obstructed them in two successful sessions.
To get round this hurdle there is already talk of the government creating lots of additional Tory peers. Such a solution has never actually been implemented, but it has been threatened twice before. In 1910 the Liberals were required to hold another general election before George V would agree to such a move, at which point the Lords caved in. In 1832 William IV tried and failed to change the ministry which had been overwhelmingly elected in 1831 before agreeing to new peerages, at which point the Lords also caved in. Both of these historical precedents are thus different from the situation in 2018, as in both cases the government had a substantial mandate from the electorate to push through its programme. Given the 2017 election result, Theresa May would be on much shakier ground if she claimed that she had a similar mandate for peerage creations now.
All the indications are, however, that their Lordships are likely to prove less recalcitrant than their predecessors in 1832 and 1910. This brings us to a third scenario. In light of the lack of a democratic mandate for the manner of leaving the EU the idea of another referendum has been floated. The view is that this will provide democratic imprimatur for, or rejection of, the terms that eventually emerge from the exit negotiations. Given the worthlessness of so many of the Leave leaders’ promises in the 2016 referendum, there may be excellent political reasons for this idea. The question is how might such a device work constitutionally.
The first problem is whether the lack of a mandate currently can retrospectively be plugged. Does this not undermine the whole idea of a mandate, presenting the electorate instead with a fait accompli? The second, more fundamental problem is that the practice in the UK has always been that referendums are only held after they have been promised in a general election manifesto. In other words, to hold a new referendum itself requires a mandate. No such mandate can be claimed without another general election. The current government are unlikely to make the same mistake twice though. Instead, mandate or no mandate, they will continue to plough on propped up by the DUP, despite the dubious constitutional nature of their position, because they can do no other. That weak parliamentary position is the narrow basis on which they will continue to claim a mandate for the enormous and largely unforeseen changes that Brexit will bring to Britain. However, if Remainers wish to overturn that in a new referendum then they need the mandate of a new election first. Their best hope could be that the government is driven to holding one in order to justify the creation of new peers. Only the adventurous, however, would bet on such an outcome.