How can we evaluate Brexit?

by Professor Phil Syrpis,  University of Bristol Law School

This article examines attempts to evaluate Brexit. Brexit is a ‘complex event’ which involves far-reaching political, economic, legal and social change. When, as in relation to Brexit, the stakes are high and opinions are entrenched, methodologies are bound to attract critical attention. In the light of the prevalence of ever-louder claims that ‘Brexit has failed’, this piece discusses the inherent difficulties in making such an apparently definitive assessment of ‘a complex event’. In the specific case of Brexit, the near absence of settled objectives compounds the difficulties, with the result that the criteria on which evaluations are based will inevitably be contested.

I introduce three broad ways in which evaluations of ‘complex events’ may be attempted. First, ‘complex events’ may be evaluated through a theoretical lens. Second and third, they may be evaluated empirically. Within the second group, I distinguish between empirical analysis at the ‘macro’ and at the ‘micro’ level. As time passes, and as the effects of ‘a complex event’ are felt, there tends to be a shift towards empirical analyses. Even analyses primarily based on theory tend to incorporate empirical components, typically to demonstrate that there are facts ‘on the ground’ which back up the theory.


In the lead up to Brexit, all sorts of claims were made, by the leave and remain campaigns, and many others, about the effects which Brexit might have. The resonance or appeal of the wide-ranging claims made by the leave side – referencing among many other things, sunlit uplands, £350 million per week for the NHS, frictionless trade and democratic renewal, together with a critique of the so-called ‘project fear’ narrative deployed by the remain side – was no doubt at least in part responsible for the narrow referendum win for leave in 2016.

It has become painfully clear that the reality of EU membership and world trade is not well understood. This has created a space for two set of claims. First, economic and legal claims, about the effects which leaving the single market and customs union (and, more recently, signing various free trade agreements) might have on trade with the EU and the rest of the world and on the size and health of the UK economy. And, second, more abstract political and philosophical claims, for example, about the impact of EU membership and Brexit, on sovereignty. The various claims are difficult to weigh, and while some of the arguments presented are manifestly wrong, there are legitimate differences about, for example, the relative importance to attach to the various claims.

Another reason for the appeal of the leave claims was the determined refusal of the leave side to associate itself with any particular version of Brexit. Brexit necessarily entails the replacement of one set of relationships with the EU and the rest of the world, with a different set of relationships (including the option of no relationship at all). In the months, for example, of ‘leave means leave’, or the later enthusiasm for ‘go WTO’, little thought appeared to be given to how best to reconfigure those relationships. Even now, we frequently hear that Brexit gives us the ability to make our own sovereign choices, and that if we do not make ‘good’ choices it is our fault, and not the fault of Brexit, which, according to these accounts, is simply an empowering device.


Empirical analysis

However, now that Brexit has taken concrete form, it is possible, albeit with caution, to begin to evaluate the specific form Brexit which the UK has, in the tortuous years since 2016, embarked upon.

It is necessary first to acknowledge that the UK’s post-Brexit relationship with the EU, based on the Withdrawal Agreement and the Trade and Cooperation Agreement (TCA), and with the rest of the world, is ever evolving; that the building of relationships post-Brexit is a process rather than an event. To give just a few examples: there are a variety of Joint Committees in which representatives of the UK and the EU regularly make decisions – for example in relation to the UK’s participation in Horizon programmes, or the ability to speed up passport checks; the Windsor Framework may be renegotiated as early as 2026; and there a number of ‘grace periods’ still in application, such that the full effects of some Brexit changes have yet to be felt. Away from relations with the EU, new trade agreements (such as the CPTPP) may improve UK access to some markets. Far-reaching changes may occur in the UK, for example in relation to the regulatory regime. Each of these may, or may not, turn out to be material to any evaluation.

Seizing on the uncertainties inherent in Brexit, some argue that Brexit is not (yet) ripe for empirical analysis; we may, it is said, need to wait, perhaps for 50 or 100 years, before we are able fairly to evaluate it. That argument should be given short shrift. It is important, not least in order to avoid negative consequences, to be able to evaluate – albeit provisionally and with an eye on what might cause provisional evaluations to change – ‘complex events’ in real time, as they are in the process of ‘reification’. That said, thought should be given to the nature of the evidence used to evaluate Brexit, and the strength of any conclusions which may be drawn.

I distinguish two forms of empirical analysis of Brexit (doubtless there are other ways to cut this particular cake). First, there are ‘macro’ analyses, which essentially attempt to compare the UK, or a sector of the UK economy, with what it would, or might, have been like, absent Brexit. The problems with this sort of approach are manifold. Most obviously, there is no counterfactual – we simply cannot know what would have happened absent Brexit. Moreover, other ‘events’ have intervened, for example, COVID, the war in Ukraine, and the Liz Truss premiership. While there have been ingenious attempts to build ‘doppelganger’ models, and to compare the UK’s performance with that of other comparable economies which have experienced similar external shocks, the methodologies employed are consistently criticised. Nevertheless, these analyses paint a stark picture, with the Office for Budget Responsibility, for example, forecasting a long-term 4% cut in GDP.

These ‘macro’ analyses, which can be economic or legal, coexist with a growing number of ‘micro’ analyses, evaluating the effects of Brexit on individual industries, individual businesses, and individual people. These analyses are able to demonstrate not only the existence of an effect (selling my goods in France is more difficult; going through the port of Dover takes more time), but also to point towards reasons for the effect (in the examples above, because I have to fill in extra forms and comply with extra rules; and because my passport needs to be stamped). A downside of this sort of analysis is that it is, or may be, anecdotal, and that negative effects may, fairly or unfairly, be attributed to fault on the part of individuals and businesses who did not adjust to the new status quo.

What is striking about the ‘micro’ analyses, is that while it possible to find many hundreds of instances in which the changes wrought by Brexit have made things impossible, or more costly or burdensome, there are very few examples of things which have been made easier (for example, perhaps, as a result of the ‘better’ regulation the UK now has, or as a result of the opportunities to trade more easily with the rest of world). The frequency with which the – contested – example of the vaccine roll-out is deployed speaks volumes. It is not impossible that such benefits will come in time, but it is striking that there has not been a targeted attempt by the Government to use the opportunity provided by Brexit to target specific problems or burdens. Instead, as with the Retained EU Law Bill, we see instinctive opposition to things deriving from the EU (including, for some, the ECHR), coupled with airy rhetoric about our reclaimed ability to make our own, sovereign, choices.


There appears to be the beginnings of a consensus, echoed this week by Nigel Farage, that Brexit has failed. And there is indeed mounting evidence that public opinion is turning towards disenchantment with the way Brexit has played out. However, any claim that Brexit has failed, is difficult if not impossible to substantiate without reference to what it was that Brexit was expected to achieve (and we know that there is no shortage of, sometimes mutually incompatible, possibilities). There is little doubt that it will continue, to the end, to be a success to some. Nevertheless, there are some conclusions which it is possible, some 7 years on from the referendum, to draw.

First, Brexit has had negative effects on the UK economy. It has done so by making trade with the EU significantly more difficult than it was. Put simply, membership of the single market confers advantages which the TCA does not. The gains the UK may make in relation to trade facilitation with the rest of the world are – by a huge margin – unable to compensate. The size and nature of this effect may be sketched in general terms, based on a variety of theories and observations of the ‘macro’ performance of the UK, reinforced by ‘micro’ analyses of the situation of individuals. Over time, it is possible (and I would suggest, likely) that the extent of the negative effects will lessen as people and businesses adjust to the new reality.

Second, the opportunities of Brexit seem to be limited. It is possible (albeit not in the geographical sense) to replace proximity with the EU with proximity with other parts of the world, but the forging of new relationships comes with its own compromises. The fact that you can’t reach agreements with other states unless you… reach agreement with them, seems to escape some. And if people think that it is only the EU which would presume to make demands of the UK in a trade negotiation, or that it is only the EU whose interests may sometimes diverge those of the UK, then, as they say, good luck with that.

And third, and last, just as the referendum was divisive, and the steps taken to realise Brexit were divisive, so too will be the reckoning. Even if failure is acknowledged by some of the leading protagonists, it is likely to be on the basis not of any inherent flaw in the Brexit project or ideal, but instead because Brexit has not been implemented properly. As to what proper implementation might involve, views will continue to differ.

‘Complex events’ are, by their nature, difficult to evaluate. The criteria on which evaluations, based both on theory and on empirical analysis may be based are inevitably contested, as are, for example, questions relating to causation and opportunity cost. In the case of Brexit, much of the contestation is the direct result of the assimilation a range of, sometimes mutually incompatible, objectives. If only more thought had been given to the identification of those objectives, and to the legal, political and economic changes required to enable them to be realised, it would have been far easier to identify criteria according to which success – and failure – could be evaluated.

A version of this piece was published in West England Bylines on 7 June 2023. You can access the original at  Evaluating Brexit (

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