Simply blocking a second Scottish independence referendum could increase support for one

The Scottish government is committed to holding a second independence referendum before 2021 if the UK leaves the EU. But, as it did in 2014, it will need Westminster’s approval to do so to put any vote on Scottish independence beyond legal doubt.

A Conservative government is unlikely to agree to do that. First Minister Nicola Sturgeon’s last request in 2017 was flatly rejected by Theresa May, and during the Tory leadership contest candidates were lining up to rule out another vote.

But given the constitutional sensitivities highlighted by Brexit, a government determined to keep the Union together must be careful not to imply that the Scottish people should not have the right to determine their own future.

This is about who should have the power to hold the referendum, not just whether one should be held

It is not clear whether the majority of the Scottish public support a second independence referendum but even those opposed might still think it is up to the Scottish Parliament to decide to hold one. In a recent poll, 50% of people thought the Scottish government should have the ‘final say’ on whether there should be a second referendum compared to just 36% who thought it should be the UK government.

Perceptions of the UK government obstructing the Scottish Parliament would play into nationalist narratives, potentially increasing support for independence itself.

If the UK government wants to prevent independence, it must not rely solely on its power to block a referendum. Instead, it needs to shift the debate to focus on what the Union can do for Scotland.

Boris Johnson has promised to make the positive case for the Union and “renew the ties that bind our United Kingdom”, but the prime minister’s recent visit to Scotland was not well received. His government has more work to do.

There are unresolved constitutional questions underlying the debate on Scottish independence

At its core, this is about the principle of self-determination and where sovereignty lies in constituent parts of the UK. These are fundamental constitutional questions that remain unresolved, as the Institute for Government has argued in two recent reports on the state of devolution after two decades.

Legally, the UK Parliament remains sovereign, meaning that the Scottish devolved institutions derive their authority from UK statute, not the Scottish people. But in the 20 years since devolution, differences in understanding of constitutional principles in each of the four nations of the UK have been exposed.

This has been made more apparent by Brexit, where Scotland is being taken out of the EU despite the majority voting to remain. The Scottish government has claimed to be increasingly side-lined in negotiations, and for the first time the UK Parliament legislated on a devolved matter without the consent of the Scottish Parliament.

The UK government should expect a request soon

The Scottish government is already taking steps to prepare for another vote on independence. In May, it introduced the Referendums (Scotland) Bill, which would allow Scottish minsters to call an independence referendum as soon as the power to do so is devolved.

With this, and with no deal looking increasingly likely, a formal request from the Scottish government for that power looks imminent. The UK government must plan its response carefully.