Anas Sarwar must put pressure on Sir Keir Starmer if he becomes Prime Minister next month to remove a block on Holyrood's gender law "if he has the remotest shred of commitment to the rights and integrity" of the Scottish Parliament, according to Patrick Harvie.

The Scottish Greens co-leader made the demand to Mr Sarwar during an interview with the Herald on Sunday after he and fellow co-leader Lorna Slater unveiled their party's general election in Edinburgh on Thursday.

Addressing candidates, activists and journalists Mr Harvie said Sir Keir must lift the Section 35 order on the Gender Recognition Reform (GRR) Bill which was imposed by Scottish Secretary Alister Jack after the legislation was passed by MSPs in December 2023 when Nicola Sturgeon was first minister.

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The legislation would have introduced a process for a person to self declare their gender, removing a requirement for a diagnosis of gender dysphoria for a person to apply for a gender recognition certificate, as well as lowering the minimum age and shortening the period the applicant would have to live in their preferred gender.

Mr Jack's use of the Scotland Act's Section 35 order was the first time it had been applied since devolution in 1999 and meant the bill could not receive royal assent and implemented in Scotland. He said the order was used as the legislation had an adverse effect on reserved matters. In particular, that the bill would affect the matter of ‘equal opportunities’ – specifically the Equality Act 2010, which makes ‘sex’ a protected characteristic.

In his speech launching the Scottish Greens manifesto on Thursday, Mr Harvie said Sir Keir should remove the Section 35 order.

Later, interviewed by the Herald on Sunday, he was asked if he would write to the Labour leader if he became Prime Minister to request the block is lifted.

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"I think that is a question we should be putting to Anas Sarwar. He voted for the bill. Keir Starmer is more likely to open a letter from Anas Sarwar than he is from me I would imagine," he said.

"The leader of Scottish Labour is going to have an important responsibility to play there. He has voted for legislation in a fully devolved area, passed by the Scottish Parliament, by an overwhelming majority on a cross party basis, after the most extensive and detailed scrutiny of any bill that has been passed in a quarter of a century of this parliament's existence.

(Image: Gprdon Terris)UK Labour leader Sir Keir Starmer campaigning with Scottish Labour leader Anas Sarwar in Whitburn, West Lothian on Friday.  Photo: Gordon Terris.

"If he has a remotest shred of commitment to the rights and integrity of this parliament and its authority to pass legislation to fulfill manifesto commitments that have been made repeatedly by most political parties then he will insist that the new UK Government removes that Section 35 order. It was an abuse of power by the UK Government, it was never intended in the Scotland Act simply to block policy simply because the UK Government had a different policy.

"There is absolutely no technical reason why you can't have slightly different systems operating north and south of the border. So the pressure needs to be on Scottish Labour who voted on this legislation to say to UK Labour you need to not do what the Tories have done and use the power of the UK Government."

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During a visit to Scotland on Friday, Sir Keir ruled out lifting the block on the GRR bill.

"No, there would be no change of position on that," Sir Keir said.

"I think there's a lot to learn about gender self-ID from the way in which it's been dealt with here in Scotland, which is why we've got a different proposition in our manifesto."

Mr Sarwar, who was campaigning alongside Sir Keir, added: “The court has made it very clear that the law as it currently stands doesn't comply with the Equality Act and the primacy of the Equality Act is very, very important.”

However, speaking to the Herald on Sunday last month, the Greens equalities spokeswoman Maggie Chapman, said the court ruling was only over whether the UK's use of the Section 35 order was lawful and did not rule on the substantive issue over whether the GRR Bill did impinge on the UK Equality Act.

The Scottish Government made a legal challenge to the UK Government's use of the Section 35 order but lost its case with the Court of Session ruling that the the use of the order was lawful.

The Bill remains on the statute book and could be become law should the UK Government allow it.

A Scottish Government spokesperson has previously said: “The GRR Bill was passed by the Scottish Parliament. If the UK Government lifted its legal block – the section 35 order - it would become law.

“The problem is that the current UK government has said they will not. The Scottish Government’s position is simple - UK Government should lift their section 35 order.

“They have made clear however that they will not, and until they do, it is simply not legal to implement the legislation.”