Gina Miller told Scotland on Sunday she supported Nicola Sturgeon’s attempt to use the case to secure a say for Scotland on the type of Brexit deal negotiated by the UK government.
The Scottish Government this week confirmed that it would join the legal action when it is heard by the Supreme Court following an appeal by UK ministers.
Earlier this month the High Court ruled that the government must consult Westminster before triggering Article 50 of the Lisbon Treaty to start the two-year exit process from the EU. The appeal will be heard by a full panel of 11 senior judges on 5 December.
Miller said Sturgeon was right to “do what’s best for Scotland” and reflect the majority vote of Scots to stay in the EU.
The 51-year-old London investment fund manager, who has faced threats and abuse for pursuing the case, said she hoped victory at the Supreme Court would require the government to share more of its Brexit negotiating position.
She also hit out at politicians for failing to condemn attacks on the judiciary from sections of the media over the case.
“I expected some backlash because everything to do with Brexit is so emotionally charged,” said Miller. “But I’m extremely disappointed in certain media who are being divisive and fuelling a lot of the threats in the way they are reporting the case. Every turn of phrase is poisonous and discriminatory, or racist, or sexist, and they have to take responsibility for some of the divisions that are happening in society.
“Politicians have also been far too slow in coming forward in condemning the attacks on myself and the judiciary.”
Downing Street has said it will not provide a “running commentary” on Brexit talks with Brussels in order to protect its negotiating position.
However, Scottish and Welsh ministers have complained about the lack of detail being shared in discussions with UK counterparts.
Miller said it was “inevitable” that the UK Government would have to consult more widely about its plans if she is successful.
She said: “There are so many more questions that need to be answered – what Brexit means, how it will be negotiated, what does the package look like, is it a pragmatic one? There are so many questions, and there appears to be no plan. It is only right that these questions are asked.”
Miller added: “Nicola Sturgeon has to represent the view of the majority in Scotland, which was to remain. She has to make sure, whatever happens, that Brexit is in the best interests of Scotland.
“As much as the Prime Minister says in the UK that Brexit means Brexit and it’s the people’s will – well, the Scottish people’s will is also very clear.”
Sturgeon says she wants the Scottish Parliament to be consulted on any Westminster legislation to approve the triggering of Article 50. That would probably take the form of a legislative consent motion voted on by MSPs.
However, Holyrood approval is a non-binding convention, and the Scottish Parliament would not have the power to block Brexit.
The First Minister has accused Theresa May of “seeking to bypass the Scottish parliament and take steps that will involve fundamental changes to the devolution settlement with no proper scrutiny here in Scotland”.
The Welsh government will also intervene in the case. Nigel Farage, the former Ukip leader, has called for a protest by 100,000 people outside the Supreme Court the day before the appeal is heard.