The UK Government has been accused of using the "nuclear option" to block controversial gender reforms passed by Holyrood.
Tory ministers last night confirmed they would use a Section 35 order for the first time since the Scottish Parliament was opened in 1999 to strike down a piece of legislation.
Nicola Sturgeon branded the move a "full-frontal attack" on devolution and promised her government would defend the Bill. SNP ministers are now considering their next move but it is expected they could launch a judicial review.
Shona Robison, the minister who guided the gender reform bill through Holyrood, said today she believed there was "no legal basis" for Westminster to challenge the legislation.
"If the UK Government thought there was a legal basis to challenge the Gender Recognition Reform (GRR) Bill, they would have done so in the Supreme Court through a Section 33 order, as they have done previously," she told BBC Radio Scotland.
"I think using this nuclear option, a Section 35 that has never been used before, I think reveals there is no legal basis to challenge it.
"It's all about politics. And I think using one of the most marginalised groups in society as a political weapon is simply outrageous."
Alister Jack, the Scottish Secretary, will make a statement later today in the Commons setting out why the UK Government has blocked the bill.
Asked if her side was "relishing a fight", Robison said: "If the UK Government had seriously had some amendments that had kept the principle of the bill - that is reforming the process for obtaining a gender recognition certificate - then they would have brought forward those suggestions.
"The principles of this bill are very clear. I am all up for discussion. But what we will not to do is throw out the principles of a bill which is helping the lives of a small, marginalised group in Scottish society."
Meanwhile, a UK Government minister claimed she found criticism of the move to the block the GRR legislation "surprising".
Gillian Keegan said Holyrood and Westminster cannot have "competing" gender and equality legislation.
She told BBC Breakfast "the Scottish Act … was set up 25 years ago within the legislation designed in this power for exactly this type of scenario".
She said that, while the power has never been used before, "now, with the Gender Recognition Act, the Secretary of State for Scotland has used this power because we can’t have two competing gender and equality legislations.
"So we need to look at that and need to work out what to do, and he’ll be setting out and making a statement later on today in Parliament."
To sign up to the Daily Record Politics newsletter, click here.
