The question of sovereignty lies at the heart of the UK’s upcoming EU referendum. Many in Britain believe that the process of EU decision-making has undermined British parliamentary democracy and that leaving the EU is the only way for the British people to regain control of their sovereignty. Chatham House Director, Robin Niblett, has published a research paper analysing this argument. Here are five key takeaways.

1) Britain already controls 98 per cent of its budget.

Leave campaigners argue that the UK spends £350 million on EU membership every week (or £18 billion every year) — money that could be spent on British priorities after Brexit. But these figures ignore the rebate and investment Britain receives from Europe. In reality, the UK’s net contribution to the EU budget in the 2014/15 financial year was £8.8 billion.

This is just 1.2% of Britain’s total public spending of £735 billion that year. Even if you add back in money spent in the UK but decided in Brussels, such as agricultural subsidies, the British parliament still has sovereign control of over 98% of public spending.

2) Britain already controls almost all of the policies British people care about.

As captured by the above Ipsos MORI poll, immigration is currently the top concern for UK voters. Leave campaigners argue that immigration policy (more on this to follow) is just one of numerous areas in which the supremacy of EU law undermines British sovereignty. This is incorrect.

The UK government sets its own laws and policies on almost every other issue of serious concern to the British public— either because the EU has no right to act or because decisions are taken by unanimity. The list of issues on which Britain has sovereignty from Brussels include the NHS, taxes, pensions, benefits, education, defence and foreign policy, among others.

3) Leaving the EU is unlikely to have a big impact on migrant numbers.

There are several reasons for this. Firstly, migration from outside the EU, which accounts for about half the total, would continue unaffected. Secondly, the UK government might have to accept continued free movement of EU workers in exchange for access to the single market. This is the case for Norway and Switzerland, who are both outside the EU but have far higher levels of EU immigration than the UK as a proportion of their populations. Finally, even if the UK was not compelled by Brussels to accept EU workers, its economy would still need EU workers to meet UK labour market demands.

It should be noted that immigration of workers from the rest of the EU has many positives. While many Leave campaigners see migrants as a drain on public services, EU migrants actually contribute more to the British economy than they receive in public services and payments.

4) Sovereignty is overrated.

Sovereignty means having the power to write the laws that govern a country. But, in a world that is increasingly interconnected, that power means very little. Sovereignty is not the same thing as being able to control the forces that affect the population.

British governments have long realised the limits of absolute sovereignty. This is why they have designed and signed up to the rules not only of the EU, but also of international organisations such as NATO, the WHO, WTO and UN — because accepting selective limits on sovereignty improves the government’s ability to deliver prosperity and security to the British people.

5) EU membership gives the UK government more control over the forces that affect British people.

UK Foreign Secretary, Philip Hammond, discusses EU sanctions against Russia with his French counterpart, Laurent Fabius, and EU foreign policy chief, Federica Mogherini, at an EU Foreign Affairs Council meeting in January 2015.

Whether the UK is a member of the EU or not, it will be affected by the decisions taken by its geographical neighbour and largest trading partner. Being inside the EU gives it a chance to shape those decisions in its favour, which it generally does successfully.

The nature of many modern challenges also lend themselves to collective, rather than independent, action. Britain could not have implemented meaningful sanctions against Iran or Russia without its EU partners. It could not have achieved recent progress on climate change without working as a bloc. And it will not be able to maximise the potential of the EU services market without shaping the rules that regulate it.

In short, being in the EU may mean a slight loss of absolute sovereignty. But we have seen that this loss is minor — and that the benefits are significant.