Less than a month after becoming Scotland’s first minister, Humza Yousaf has announced that his government is taking the UK government to court in a row about gender recognition.

It sends Holyrood and Westminster into a head-on constitutional fight – with those campaigning for and against the law itself stuck in the middle.

So what’s going on – and how do Scots feel about the proposed reforms?

What is the Gender Recognition Reform bill?

Scotland’s Gender Recognition Reform bill was approved by MSPs at the end of last year.

The legislation would make it easier for people to change their legal sex by removing some of the barriers to getting a gender recognition certificate (GRC).

Specifically, GRC applicants would no longer need a medical diagnosis of gender dysphoria, which the NHS describes as “a sense of unease that a person may have because of a mismatch between their biological sex and their gender identity”.

The law would also reduce the time an applicant has to live in their “acquired” gender from two years to three months (with a further three-month “reflection period”), and lower the minimum age requirement from 18 to 16.

Many trans campaigners had welcomed the reforms, saying that they would lessen the procedural and medical burdens on trans people seeking legal recognition of their acquired gender.

But some women’s rights groups argued that the proposed law was open to abuse by predatory men whom they feared would use policies intended to help trans people.

What is the UK government doing and what is Section 35 of the Scotland Act?

After much political wrangling in Holyrood, the bill eventually gained assent of a majority of MSPs in December.

Normally, when a bill reaches this stage, it is brought to the monarch for royal assent – the final seal of approval to turn it into law.

But under the Scotland Act – the UK-wide statute that sets the terms of Scottish devolution – Westminster has powers to prevent Scottish bills becoming law if certain conditions are met.

Section 35 of the Act allows UK ministers to intervene if the planned Scottish law interferes with “reserved” matters – that is, areas of policy that belong to the UK, rather than the Scottish, government.

In January, the UK government triggered section 35, saying the Gender Recognition Reform bill would have “an adverse impact on the operation of Great Britain-wide equalities legislation”.

Some aspects of equalities policy are reserved to Westminster and London fears the Scottish legislation could interfere with the Equality Act 2010 that covers England, Scotland and Wales (parts of it also apply in Northern Ireland).

Writing to the then-first minister Nicola Sturgeon, the UK government’s Scotland secretary Alistair Jack said, “I know we both have a shared desire to protect the rights of both women and transgender people”.

But, he said, Scotland’s proposed reforms would have impacts on “the operation of single-sex clubs, associations and schools, protections such as equal pay and chilling effects on single-sex spaces”.

He also raised concerns about the Scottish bill’s provisions to allow 16- and 17-year-olds to change their legal sex, which is not possible elsewhere in the UK – as well as the possibility of the bill “allowing more fraudulent or bad faith applications”.

What is Humza Yousaf doing about gender recognition?

Before her resignation as first minister in February, Nicola Sturgeon had hinted at plans to challenge the UK government’s section 35 order in court.

She described the block as a “full-frontal attack on our democratically elected Scottish parliament and its ability to make its own decisions on devolved matters”.

Now, after just a few weeks in the job, Ms Sturgeon’s successor Humza Yousaf has confirmed that his government will bring the case to court.

How popular is Scotland’s Gender Recognition Reform bill?

In YouGov polling in December, a majority of Scottish voters said they opposed three key measures in the bill that would make it easier for someone to change their legal sex.

Some 60 per cent were against removing the dysphoria diagnosis requirement, 66 per cent rejected lowering the minimum age to 16, and 59 per cent opposed reducing the waiting time from two years to six months.

And crucially, those policies were also rejected by a majority of SNP voters (59 per cent, 63 per cent and 56 per cent against, respectively).

In another YouGov poll in January, some 40 per cent of Scots agreed with the statement “the Scottish government’s changes are the wrong thing to do, and the UK government are right to block them”. This was the most popular answer among Scottish and English respondents.

A further 19 per cent of Scots said they thought the gender reforms were “the wrong thing to do, but it is wrong for the UK government to try and block them”.

It’s a similar picture in more recent polling by Conservative peer Lord Ashcroft.

His survey in February found that only 22 per cent of Scots, and 36 per cent of SNP voters, agreed with the statement “I support the bill and the UK government is wrong to block it”.

The Tory pollster sums up his results as showing: “By 50 per cent to 28 per cent, Scottish voters said they would rather have a law made in Westminster that they agreed with than a law made in Scotland that they disagreed with.”

Across Great Britain, polling in January by Redfield and Wilton found a more mixed picture.

Overall, British adults were more likely to oppose removing the requirement for a dysphoria diagnosis than support it (38 per cent against versus 28 per cent in favour).

But there was a larger group of people who said they neither supported nor opposed the measure (28 per cent) than we saw in Scottish polling.

This might reflect the fact that this policy has not been as prominent in UK-wide politics as in Scotland, meaning more people have yet to make up their minds.

Nevertheless, Brits were clearer on the question of lowering the age of a legal sex change to 16 – with 54 per cent opposing, versus 22 per cent supporting the proposal.

Some 50 per cent of British adults backed the idea of the UK government blocking the Scottish bill “in order to safeguard women’s rights in England’s schools, hospitals and prisons”, as the pollsters put it. Just 13 per cent of Brits said they would oppose the move.