If Britain were to vote to leave the EU in June would it regain the sovereignty that those in favour of leaving argue it has lost? The answer is no. The very fact that the UK is holding this vote proves that it remains sovereign. The referendum is not about sovereignty. It is about how best to exercise the country’s power.

In his pamphlet, Sense on Sovereignty, published in 1991, Sir Noel Malcolm explained that the starting point for any debate on sovereignty should be the distinction between power and authority.

A sovereign state possesses the authority to make and implement valid law. A state’s power might be weak, but it is subject to no higher authority. Today, the fact that lawmaking institutions are democratically accountable creates legitimacy. An illegitimate government is a despotism.

States exist to serve the interests of their citizens. They can achieve that objective only through co-operation with other states. For this reason, the UK has signed 14,000 treaties. Legally, the UK could withdraw from them all.

Since it does not wish to become North Korea, it will not do so. Treaties do not undermine sovereignty, but express it. They constrain the exercise of sovereignty, with the intention of making it more effective. They do so by delegating powers. Some of these powers are matters of life and death. The UK is a member of Nato, for example, because it believes, rightly, that it enhances the security of its citizens.

Limit

Is the EU different from other treaties? The answers are: “no” and “yes”.

The answer is no, because the UK can clearly withdraw. This would be complex and painful and might lead to the break-up of the UK, with Scotland deciding to leave. But nobody would seek to stop it. Thus the UK’s membership of the EU does not limit its sovereignty. That remains with the British people’s elected representatives in parliament.

The answer is yes, because, as a member, the UK is bound by the treaties, by rulings of the European Court of Justice and by decisions reached by the European parliament and by qualified majority voting in the Council.

The political question in the referendum is not about sovereignty but about the delegation of powers within a treaty-governed system of particularly far-reaching obligations.

Future changes in the relationship between the UK and the EU could make membership effectively irreversible: abolition of the UK parliament would be one, and transfer of full powers over taxation or security could be another. Even membership of the single currency could be viewed in the same way. But, without such far-reaching changes, the UK remains sovereign.

Membership

The question for the UK is whether EU membership strikes a sensible balance between accountability and effectiveness in the exercise of those delegated powers. Yes, the UK is committed to things that many want to avoid – free movement of people, for example. But how does the balance look, overall?

The defects of the EU on accountability are real. The single currency is the best example: the gulf here between accountability, still largely national, and decision-making, now largely supranational, is glaring. Yet the UK is not part of this. The defects of the EU over democratic accountability cannot be solved without truly supranational politics. This is highly unlikely. It would also be highly unwelcome to the UK, since it would terminate national sovereignty.

Yet the EU is also about effectiveness. Charges that president Barack Obama is being hypocritical in arguing in favour of UK membership of the EU miss the point.

The US is a superpower: it does not need such an arrangement to influence the world; the UK is not a superpower: it does.

Margaret Thatcher accepted the argument for qualified majority voting, to create a single market, for a good reason: without it, that would probably be impossible.

Goals

A salient issue is whether the powers delegated to the EU go beyond what is appropriate to the goals the UK seeks. The answer, notes a report from the Centre for European Policy Studies, is no.

The UK’s “balances of competences” review concluded that the powers delegated were appropriate to the goals the UK wanted to achieve. Repatriation of competences duly vanished from the government’s negotiating goals.

The question then is whether membership of the EU is an appropriate exercise of UK sovereignty.

Yes, we can identify difficulties over accountability. Yet we also see huge gains in effective exercise of power. Membership gives the UK a say in the future of the European continent.

It gives it a potent voice in the positions on global affairs of one of the world’s most powerful actors. It magnifies the UK’s ability to influence global developments that are of vital interest to the welfare of its citizens, such as over climate. It gives it, not least, favourable terms of access to its biggest market.

Should we seek substantial further delegation of powers to the EU? Definitely not. But the benefits of what the UK now has - most of the advantages with few of the disadvantages – seem not just evident, but truly substantial.

Criticism

The strongest criticism of Mr Obama was that he spoke for US interests, not the UK’s. This is doubly mistaken.

First, US perceptions of US interests are themselves important in defining UK interests.

Second, candid friends often see one’s own interests better than one can oneself. UK sovereignty is not at stake in this referendum. It is, instead, proved by it.

The referendum is rather about whether the UK has delegated excessive powers to the EU.

The big achievement of David Cameron’s negotiations is to establish that the UK will go no further. Our partners appear to accept this. That being so, the best balance between accountability and effectiveness lies with the status quo.

The price of Brexit will be much diminished effectiveness and, at best, moderately greater accountability. That price is far too high.

Copyright The Financial Times Limited 2016