A landmark court decision on whether the UK Government can veto Holyrood gender reforms is expected on Friday.

Lady Haldane is scheduled to give her judgment in the case after taking evidence over two days of hearings in September.

Barring any last minute delay, her written judgment is expected to be published around noon.

It will be a key moment for Humza Yousaf, who launched a legal challenge against the UK Government’s action as a matter of principle. 

It has so far cost taxpayers almost £230,000 in Scottish Government costs alone.

READ MORE: Scottish ministers spend £230K on gender reform legal challenge

It is also a critical decision for Scottish Secretary Alister Jack, who used an unprecedented order under Section 35 of the 1998 Scotland Act to halt legislation passed at Holyrood.

Mr Yousaf promised during the SNP leadership contest in the spring that he would contest the veto of the Gender Recognition Reform Bill (GRR).

The Bill was passed with cross-party support by 86 votes to 39 in December 2022.

The aim was to speed up and simplify the process for a trans person to change their gender in the eyes of the law by obtaining a gender recognition certificate (GRC).

Under the current UK-wide system, this takes at least two years, involves a medical diagnosis of gender dysphoria and is available only to those aged 18 and above.

The Holyrood GRR Bill would cut the waiting time to three to six months, replace a medical diagnosis with self-declaration (Self-ID) and reduce the age threshold to 16.

But before the Bill could become law, Mr Jack vetoed it in January with the Section 35 Order.

He argued that although the issue was within Holyrood’s powers, the Bill nevertheless cut across UK-wide equality law and could pose a risk to single-sex spaces.

Nicola Sturgeon, who was First Minister at the time, called it a full-frontal assault on devolution.

The Scottish Government went to the Court of Session in September in a bid to overturn the order in a judicial review, arguing it was unlawful and irrational.

The Government’s top law officer, the Lord Advocate Dorothy Bain KC, argued Mr Jack’s decision was also based on inadequate and irrelevant considerations.

She said the veto had been used because of a “policy disagreement” between London and Edinburgh rather than because of a genuine legal concern. 

READ MORE: Court battle over Holyrood gender reform ends day early

The UK Government said Mr Jack had been legally entitled to act as he did, had acted in good faith, and dismissed Ms Bain’s “policy disagreement” argument as a “red herring”.

After submissions, Lady Haldane called the case “unique, very interesting and challenging”.

The losing side will be able to appeal to the Inner House of the Court of Session; the loser there will be able to appeal for a final ruling to the UK Supreme Court.

If the Scottish Government loses tomorrow, Mr Yousaf will be under pressure from his Green coalition partners to take the case all the way to the Supreme Court if necessary.