David Cameron’s Critical Mistake: Brexit as Constitutional Politics


William Partlett & Zim Nwokora

Melbourne Law School & Deakin University

In the ongoing drama of Brexit politics, it can be hard to know where to start with an evaluation. In this post, we want to assess a key mistake made in setting up the UK’s referendum on EU membership that took place on 23 June 2016.

Many have argued that David Cameron, then Prime Minister, should never have called a referendum. According to this view, he did so mainly to “manage” his internal party problems. Others have argued that the referendum was a sensible approach to what has been a long-festering sore in British public life, the state of the marriage between the UK and the EU. Another issue that has been voiced in this debate is whether the process leading up to, and including, the public vote was a sound one. Many have debated whether the “Remain” and “Leave” campaigns conducted themselves in a manner that was lawful and consistent with fundamental democratic norms.

We will not consider these questions.  Instead, we want to focus on a neglected question: The precise threshold or “decision rule” for a successful referendum result.  In June 2016, it was assumed that Britain would exit the European Union if a simple majority (50% +1) of Britons voted to do so. We think this was a mistake.  In fact, we argue that a decision of Brexit’s magnitude should require more than a simple majority of Britons, something like 60%. 

Our views on this are outlined in a recent article exploring two forms of politics in democracies: “constitutional politics” and “ordinary politics.” The paper’s core argument is that these forms of politics seek different ends and have far different consequences. This difference means that these forms of politics should be structured differently – and one of these is that the rules for reaching a decision should be different.

Ordinary politics produces legislation, amendments, and executive decisions that can later be reassessed. If the government is out of step with public sentiments, we should expect that the electoral process, as well as other accountability mechanisms such as political parties, will change them.  Over time, this process should ultimately ensure a reasonably close correspondence between popular preferences and policy outputs.  In producing these kinds of outputs, therefore, ordinary politics should use simply majoritarian (50% +1) decision rules.  In most parliamentary systems, we see this reflected in the simple majority voting rules for passing legislation in parliament.

Constitutional politics, by contrast, creates and alters underlying political and institutional relationships. Because many of these rules actually structure ordinary politics themselves, they are more difficult to reverse or reassess. Accordingly, the kind of politics that produce these types of outcomes is different from ordinary politics.  In making decisions of this elevated importance, constitutional politics should utilize super-majoritarian decision rules. For instance, in Australia, Section 128 of the Constitution requires a double majority for a referendum to successfully amend the constitution: (i) an overall national majority of voters, and (ii) a majority of voters in a majority of the states (i.e. at least four out of six states).  In the United States, Article V of the Constitution also requires super-majorities to make constitutional changes, including requiring three quarters of the states to approve any constitutional change. David Landau and Rosalind Dixon discuss the functional importance of this kind of constitutional entrenchment in their article Tiered Constitutional Design.

To put it another way, and paraphrasing Daniel Kahnemann, in ordinary politics “thinking fast” is fine and simple majoritarian rules are appropriate. In constitutional politics, by contrast, society needs to “think slow” and therefore needs decision rules that encourage consensus building and inclusiveness.

What are the implications of all this for the Brexit referendum? The most important is that the Brexit decision should have been understood as a decision of constitutional politics, precisely because of the vast consequences of leaving the EU for Britain’s constitutional arrangements (including, but not confined to, the delicate relationship between England, Scotland, Wales, and Northern Ireland and the status of EU-based protection of individual rights).  From this standpoint, one of David Cameron’s biggest mistakes was to organize a referendum that could lead to Britain exiting the EU if “leave” was supported by “50 per cent + 1”.  Instead, a heightened threshold for success in the referendum should have been chosen.  This threshold ultimately might not have led to a different outcome; but it would have required far more support for a break with such important, long-term constitutional implications for the United Kingdom.   

William Partlett is an Associate Professor in Constitutional Law at Melbourne Law School

Zim Nwokora is a Senior Lecturer in Politics and Policy Studies at Deakin University (Australia)

Suggested citation: William Partlett & Zim Nwokora, ‘David Cameron’s Critical Mistake: Brexit as Constitutional Politics’ IACL-AIDC Blog (1 April 2019) https://blog-iacl-aidc.org/2019-posts/2019/4/1/david-camerons-critical-mistake-brexit-as-constitutional-politics