Scotland’s First Minister Nicola Sturgeon said on Friday she did not rule out testing the legality of calling a consultative referendum on independence if UK Prime Minister Boris Johnson’s government continued to oppose another vote.

Speaking in Edinburgh on the day the UK leaves the European Union, Sturgeon said the question of whether the Scottish Parliament had the power to agree to hold a non-binding vote on independence had never been tested in court.

Sturgeon said in her speech: “To achieve independence, a referendum, whenever it happens – whether it is this year as I want, or after the next Scottish election – must be legal and legitimate.

“That is a simple fact.

“It must demonstrate that there is majority support for independence. 

“And its legality must be beyond doubt. Otherwise the outcome, even if successful, would not be recognised by other countries. 

“And the best way to achieve that, even though it may not be ideal, is to reach agreement on a transfer of power to the Scottish Parliament, just as we did for 2014.

“It has been suggested, though, that in the absence of such an agreement, it might be legal for the Scottish Parliament to hold a consultative referendum – to establish the opinion of the Scottish people even though agreement would still be required to implement a pro independence outcome.

“So let me address that. 

“The issue of whether the specific constitutional reservation in the Scotland Act puts any form of independence referendum outside the powers of the Scottish Parliament – or instead leaves open scope for a non-binding consultative vote – has never been tested in court. 

“That means it cannot be said definitively that it would not be legal, but equally it cannot be described as being beyond legal doubt. 

“If a proposal for a referendum on that basis was brought forward it would be challenged in court. 

“If a court ruled that it was legal, it wouldn’t be a ‘wildcat referendum’ as our opponents like to brand it – it would be within the power of the Scottish Parliament.

“Should the UK Government continue to deny Scotland’s right to choose, we may reach the point where this issue does have to be tested.

“I am not ruling that out. 

“But I also have to be frank. The outcome would be uncertain. There would be no guarantees.

“It could move us forward – but equally it could set us back.

“So my judgment at this stage is that we should use our energies differently. 

“We must focus firmly on building and winning the political case for independence.

“That is necessary to win a referendum.

“But it is also how we will secure one.

And though we have made much progress – as yesterday’s opinion poll showed – we have more work to do …”