Almost eight years ago, Scots were asked: Should Scotland be an independent country? Eight years is not so long ago, historically speaking. But Brexit and a new electoral mandate have created the conditions to claim the right to ask the question again.

The Scottish Government has committed to setting out a new independence prospectus to prepare for a referendum. We can expect that membership of the European Union to be central to that independence vision, as it was in 2014.

Then, debate focused on whether Scotland would have to apply to be an EU member, or whether it could negotiate a change in its membership status from within. Now, the process is much clearer. An independent Scotland would have to apply for, and negotiate, membership through a process known as accession.

These negotiations may be long and challenging, and all 27 EU member-states would ultimately decide on Scotland’s EU membership. But as a resource-rich, European liberal democracy, with a long history of membership as part of the UK, it is reasonable to assume that membership could be agreed.

But Brexit means that EU membership would pose new challenges for an independent Scotland’s relationship with the rest of the UK. Chief among these would be the status and nature of their shared borders.

Today, the land border between Scotland and England is barely visible, save for a few signposts on the road welcoming the many people who cross it. That’s not to say the border doesn’t matter. Those living on either side belong (partially at least) to distinctive political communities, have distinctive entitlements to public services, are subject to different taxes and tax rates, and live under distinctive sets of rules and regulations.

Independence would transform the border between Scotland and England into an international border. Under any circumstances, we might expect this to reinforce the differences in the rules and regulations in place on either side of the border.

Independence needn’t necessarily make the border harder to cross. In 2014, free movement across the border would have been eased by Scotland and the UK both being members of the European Union. But, with Brexit, “‘Independence in Europe” would see the border between Scotland and the rest of the UK becoming a new border between the EU and the UK. The significance of this has been amplified by the type of Brexit the UK negotiated – outside of the EU single market and outside of the Customs Union. This has led to a hardening of the UK-EU border.

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The Brexit deal – known as the Trade and Co-operation Agreement – avoided tariffs and quotas on goods traded between the UK and the EU. But the deal still requires customs declarations and checks on imports and exports to make sure they meet conditions and standards for entry. This has led to new border controls. These are especially acute when it comes to checks on animal, food and plant products, to ensure required standards are met and to prevent the spread of disease. Many checks are experienced “behind the border”, where businesses face increased bureaucracy, for example, to ensure goods being exported are properly labelled and certified as eligible for entry into the EU market.

An independent Scotland in the EU would see these checks and controls being applied across the Anglo-Scottish border too. This is because trade crossing into Scotland from England and Wales would have to meet EU standards. Checks may be applied in the other direction too. This would necessitate some form of customs and inspection facilities on or near the Anglo-Scottish border, at least along the main trunk roads.

It is highly unlikely, however, to mean passport checks. In theory, joining the EU means signing up to the entire body of EU law. But most experts assume that Scotland would be able to secure an opt-out from the Schengen Agreement. Being part of the Schengen area has many attractions, including unrestricted movement of people across the 26 participating countries, without the need for passport controls at their shared borders. But this is matched by tight controls on the movement of people across the external borders of the Schengen zone. An independent Scotland would be highly likely to instead prioritise free movement across the Common Travel Area (CTA) it shares with the rest of the UK and Ireland. The CTA has already been given legal recognition by the European Union.

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Membership of the European Union would undoubtedly create new opportunities for citizens and businesses in Scotland, opening up free movement for goods, services, people and capital across the 30 member-states that make up the European Economic Area – opportunities that would be denied to those in England and Wales. If the Protocol on Ireland/Northern Ireland was still in place, trading relationships with Northern Ireland would also become easier than they are now because it is in the European single market for goods.

It’s possible, too, that our unique geographic and historic circumstances could generate further flexibilities in EU negotiations that reduce the impact that an independent Scotland’s EU membership would have on relations with the rest of the UK. There is a phrase I have heard several times in recent months from EU-based colleagues and visiting politicians: “Where there is a will, there is a way.”

Brexit is a process, not an event. The nature of the UK-EU relationship may evolve over time towards a softer kind of Brexit, with fewer requirements for border checks. For example, it is estimated that a New Zealand-style Veterinary Agreement could eliminate around 90 per cent of the checks that are required just now. Such changes to the UK-EU deal would have the knock-on effect of reducing the potential for trade frictions across an independent Scotland’s borders with England and Wales.

Independence, too, would be a process, and a lengthy transition period would buy time to set up new systems and ensure rules were understood by those required to follow them. There is nothing especially radical about an independent country assuming responsibility for managing its own borders.

But there is no getting away from the reality that, while the Brexit decision – imposed on Scotland against its collective will – has strengthened the political case for independence, it has added new complexities to the impact that independence could have on trading and other relations with the rest of the UK.

Nicola McEwen is Professor of Territorial Politics and Fellow of the Centre on Constitutional Change at the University of Edinburgh, and Senior Research Fellow of the UK in a Changing Europe. (@mcwewn_nicola)