Ilya Somin offers a typically thoughtful case for why a second Brexit referendum would not be a betrayal of the 2016 result. His argument, as I read it, is this: Theresa May’s likely defeat on her dreadful proposed Withdrawal Agreement grants an opportunity to reassess the wisdom of leaving the EU. Given a referendum was the means of making the decision to leave, a referendum is a perfectly legitimate mechanism to test whether the public still wants to. Ergo, deciding to ultimately Remain in a second referendum would not betray the result of the first vote.

I disagree.

A second referendum so soon would violate the U.K.’s convention of having one‐​off constitutional referendums, the results of which are respected for a generation. The U.K. has had major referendums in the past on remaining within the European Economic Community (1975), changing the general election voting system (2011), deciding whether Northern Ireland should join the Republic of Ireland (1973), and Scottish Independence (2014). The results of all these constitutional decisions have been implemented without discussion of the need to check again whether people really meant to vote as they did. In the case of the EU, the gap between the EEC vote and 2016 was 41 years.

That is why, in the government leaflet that was sent to all households during the referendum campaign urging people to vote remain, the government promised to implement the result. It told the public “This is your decision. The Government will implement what you decide.” The implication was clear: the vote would be respected and delivered upon. And the result was clear: people wanted to leave the EU. Reassessing now would be an explicit breach of that promise.

For Brexit has not been delivered. We are still in the Article 50 process, and, as it stands, the U.K. will indeed leave on March 29th 2019, with or without a deal (unless Parliament intervenes). One cannot possible say “we tried Brexit and decided it wasn’t for us” when you haven’t even left. So if the second referendum did end up with a vote to Remain, and that was upheld, it would send a clear message to the public: only results that go a certain way are respected. Such a situation would fundamentally and irrevocably undermine faith in Britain’s democratic processes.

There’s another point. Referenda are relatively rare in Britain, but they usually arise because of an overwhelming public appetite or mandate for them, being rubber‐​stamped in some local or national election manifesto. No such offerings were made by either major party at the last election.

Polling furthermore suggests the public opposes a second referendum too, as do the leaders of both major political parties. Far from a so‐​called “People’s Vote” (as if the last vote was for llamas or something) it is the unreconciled Remainer MPs in Parliament who are pushing for a re‐​run. A likely reaction to a ballot forced on an unwilling public would therefore be mass boycotts and questionable legitimacy.

Indeed, it is difficult to think of what more the British public could do to show they really mean business on leaving the EU. UKIP and an increasingly Eurosceptic Conservative party won over 50 percent of the vote in a proportional system in the 2014 European elections. A Conservative party promising a referendum won an outright majority in 2015. Both the Conservative and Labour parties promised to respect the result and leave the EU’s institutions in their 2017 manifesto. The one party that pushed to reverse the result, the Liberal Democrats, did pathetically in the 2017 election.

I understand that these results were not what many wanted — especially those who see Brexit as a blow to liberty. It is peculiar to me having lived in the EU to hear it talked about as if it some pinnacle of libertarianism that no sovereign state could better. But in judging Brexit by the near‐​term loss of free movement or the problems associated in the short‐​term with no deal, some libertarians make a fundamental category error: confusing a constitutional decision with a policy bundle.

The referendum question did not ask what the trade relationship with the EU should be, or what immigration policy might be after Brexit, or whether the UK wanted a withdrawal deal or not. It was a constitutional instruction that the U.K. wanted to leave the EU’s institutions. All that other stuff is ordinary policy decision‐​making within the domain of a sovereign polity, and Britain will as pro‐ or anti‐​liberty as its people and politicians decide.

But the referendum was about self‐​determination, and which government entities create the laws by which people are governed. To reject it or run it again would be like requesting whether the U.S. should rejoin the British empire every time a President adopts a set of policies those in Congress do not like.

Of course, at some stage the UK might want to revisit its constitutional decision. Its Parliamentarians may even agree with Ilya on the desirability of another vote before Brexit has happened. But that does not negate the fact that ignoring the first vote through not delivering on it (rowing back on a promise to do so), while defying conventions on the frequency and process by which referendums are delivered, would itself represent a betrayal of the democratic mandate.ᐧ