The leader of the Scottish government said Sunday that she will push on with her campaign to take Scotland out of the United Kingdom, even if she loses a Supreme Court case seeking authorization to call a new independence referendum.

First Minister Nicola Sturgeon wants to hold a referendum in October 2023, but the Conservative U.K. government in London has said no. Britain’s top court is due to hear arguments starting Tuesday on whether Scotland’s semi-autonomous administration can organize an independence vote without the London government’s consent.

Sturgeon, who leads the Scottish National Party, said that if her Edinburgh-based government loses the court case, she will make the next U.K. national election a de facto plebiscite on ending Scotland’s three-century-old union with England.

She did not give details of how that would work. A vote held without the approval of the U.K. government would not be legally binding.

Sturgeon said that if the courts blocked a referendum, “we put our case to people in an election or we give up on Scottish democracy.”

“It should be a last resort,” she said. “I don’t want to be in that position. I want to have a lawful referendum.”

Scotland and England have been politically united since 1707. Scotland has had its own parliament and government since 1999 and makes its own policies on public health, education and other matters. The U.K.-wide government in London controls matters such as defense and fiscal policy.