Scottish First Minister Nicola Sturgeon said on Monday any move by London to block Scotland's gender reform bill would be an "outrage" as British Prime Minister Rishi Sunak prepared to use his constitutional powers to block the legislation.
This would be the first time the British government has used its powers to bar a law passed by the Scottish parliament, setting up a clash with the semi-autonomous Scottish government.
A decision is expected in the next two days with Sunak leaning towards blocking the legislation, according to officials in the Conservative government who asked not to be named. Any such move would likely be subject to legal challenge.
"I think it would be an outrage," Sturgeon told reporters at a briefing, adding that it would be "using trans-people who are already one of the most vulnerable, stigmatised groups in our society as a political weapon".
In December, Scotland became the first part of the United Kingdom to approve a self-identification process for changing gender, including removing the need for a medical diagnosis of gender dysphoria and lowering the minimum age to 16 from 18.
The reforms, backed by the ruling Scottish National Party and other parties except for the Conservatives, will remove some of the barriers transgender people face, the SNP said.
However, the changes were opposed by some women's rights campaigners, who argued they could threaten the safety of women and girls by making it easier for predatory males to access single-sex spaces such as bathrooms.
Sunak said in December it was reasonable for the British government to look at the consequences of Scotland's reforms for women and children's safety in the rest of the United Kingdom.
Keir Starmer, leader of the opposition Labour Party, also voiced opposition to the Scottish bill, telling the BBC on Sunday that he believed 16-year-olds were too young to change their legally recognised gender.
JURISDICTION CLASH
The British government has to decide by Wednesday whether to challenge the reforms on the basis they potentially clash with UK-wide legislation, including the 2010 Equality Act.
It could invoke Section 35 of the Scotland Act to seek to prohibit the bill becoming law, an unprecedented step that would challenge Scotland's devolved powers.
Sturgeon said there "were no grounds to challenge" the legislation, adding that it did not affect the Equality Act, and that it was passed by a majority of the Scottish Parliament after lengthy scrutiny.
The first minister said a challenge would be more evidence of the British government's "complete contempt for the Scottish Parliament and for devolution in principle".
"If there is a decision to challenge, then in my view, it will be quite simply a political decision," she said.
A clash would worsen relations between London and Edinburgh.
Sturgeon said last year that Britain's next national election would be a "de facto" referendum on Scottish independence after the UK's top court ruled that her government could not hold a second vote on the matter.
(Reporting by Farouq Suleiman and Andrew MacAskill, Editing by Paul Sandle and Mark Heinrich)