Scotland's First Minister Nicola Sturgeon on Monday warned London against any bid to block a controversial Scottish gender recognition law, adding her devolved government is prepared to "rigorously" defend its powers all the way to the UK's top court.
The looming standoff over the law to make it easier for people to change gender ratchets up London's tense relations with Scotland's regional government, less than two months after the ruling Scottish National Party (SNP) saw its efforts to hold a new independence referendum stymied by the UK Supreme Court.
Sturgeon told a press conference in Edinburgh that her government is prepared to "rigorously" defend the gender legislation all the way to the UK's top court if Prime Minister Rishi Sunak steps in to block it.
"We will defend the bill in the Supreme Court," if necessary, she said.
"What I can say in general is that we will absolutely, robustly and rigorously and with a very, very, very high degree of confidence, defend the legislation," said the first minister.
Sunak is considering legal advice ahead of Wednesday's deadline for him to act.
Under devolution rules, which led to the establishment of the Scottish parliament in 1999, London can block legislation if ministers believe it will have an "adverse effect on the operation of the law".
If Sunak decides to take action, he will become the first No 10 incumbent to use the blocking mechanism.
The legislation, passed by the Scottish parliament in December, makes it easier and faster for people to officially change their gender, dropping the requirement for a gender dysphoria medical diagnosis.
The legislation allows people aged 16 and 17 to change their gender, despite efforts by some Scottish lawmakers to keep the age at 18.
It reduces from two years to three months -- or six months for 16-17 year-olds -- the time needed for an applicant to live in their new gender before it is officially recognised.
Opponents of the law fear it could present dangers to women and girls, particularly around the provision of single-sex spaces.
But the Scottish government insists it will not impact the UK's Equality Act, which allows for trans people to be excluded from single-sex spaces such as changing rooms and shelters.
Sturgeon -- who has faced one of the biggest internal rebellions of her eight-year tenure over the issue -- said the previous system to change gender was "intrusive, traumatic and dehumanising".
Officials in London are closely assessing the impact the law would have on the Equality Act before advising the prime minister, said a UK government spokesman.
"We share the concerns that others - including the Equality and Human Rights Commission and the UN Special Rapporteur on Violence Against Women and Girls - have with the Bill, particularly around safety issues for women and children," said the spokeswoman.
"Our concerns include the protection of single sex spaces, and the checks and balances included in the process of gaining a legal gender recognition certificate."