Scotland’s top law officer has been accused of using a “red herring” in an attempt to overturn the Westminster veto of Holyrood gender reforms.

The claim by Lord Advocate Dorothy Bain KC that the block was down to a “policy disagreement” between London and Edinburgh was not true, a court was told.

David Johnston KC, for the UK Government, also said another of Mr Bain’s arguments about inadequate reasoning to justify the veto was “simply off the mark”.

The comments came on the second day of a judicial review hearing at the Court of Session before judge Lady Haldane.

The Scottish Government is challenging a decision by Scottish Secretary Alister Jack to stop the Gender Recognition Reform (Scotland) Bill becoming law.

The Bill is intended to make it simpler and quicker for trans people to change their legal sex by obtaining a gender recognition certificate (GRC).

It replaces the current requirement for a medical diagnosis with self-declaration, cuts the time someone must live in their acquired gender before getting a GRC from two years to between three and six months, and lowers the minimum age from 18 to 16. 

MSPs passed the legislation in December by 86 votes to 39, but the following month Mr Jack vetoed it using an unprecedented order under Section 35 of the Scotland Act 1998.

The Lord Advocate, on behalf of the Scottish Government, yesterday argued the order should be “reduced”, or annulled, as Mr Jack had failed to meet three necessary conditions.

These are that the Bill should modify reserved law, that he should have reasonable grounds for believing it would have adverse effects on reserved law, and he should give reasons.

She said the true reason for him vetoing the Bill was a “policy disagreement” rather than a genuine legal concern, and that if he succeeded it would be tantamount to Holyrood only being able to legislate when the UK Government let it.

But responding for the UK Government’ Mr Johnston flatly rejected that argument.

He told Lady Haldane: “The reference to a veto on grounds of a policy disagreement is a red herring. 

“The sole question is whether the Section 35 preconditions are met and whether the discretion was rationally exercised. 

“And whether there is or whether there might be a policy disagreement is simply irrelevant.”

He went on: “There's simply nothing in the material before the court to allow the court to reach that conclusion [about a policy disagreement]. There's nothing in the order. 

“There's nothing in the submission or the drafts of the advice given to the Secretary of State which are before the court which suggests anything other than a good faith attempt to take a decision under Section 35.”

Mr Johnson said the making of the Section 35 order did not violate or "rub up against" any constitutional principles and rejected Ms Bain's claim that it was an "unfettered" power, saying "nothing could be further from the truth".

He argued the court should only intervene if it was satisfied that "no reasonable Secretary of State' could have made the decision which Alister Jack did.

He said the GRR Bill did modify "in substance" Section 9 of the UK-wide Gender Recognition Act which deals with GRCs as it would lead in pratice to more people, and a different "cohort" of people, being able to obtain Scottish GRCs.

The Lord Advocate's claim the GRR Bill did not modify the operation of this reserved law - and was therefore invalid - relied upon an "excessively formalistic" view, he said.

Ms Bain yesterday argued Mr Jack had failed to inform himself adequately before making the Section 35 order by drawing on scant, irrelevant and biased material.

Mr Johnston rejected that, saying Mr Jack had taken advice from the Cabinet Office's Equality Hub and the Equality and Human Rights Commission and other sources which had informed Holyrood's consideration of the Bill.

It was not surprising that many of the views he considered were about possible adverse effects, rather than supportive, as adverse effects were for him to consider.

He said that having considered adequate information, it followed that his decision was therefore "within the range of reasonable decisions" open to him.

He also gave short shrift to the Lord Advocate's claim that Mr Jack had failed to take into account the experience of other countries with self-ID.

He said the evidence base was thin, there were different forms of self-ID, and no relevant country had constitutional arrangements akin to that of the UK and Scotland.

Any comparisons were of "very limited assistance" to Mr Jack and the court.

He also said that Ms Bain's argument that the reasons Mr Jack included in the Order were inadequte were "simply off the mark", and that she had not identified anything in the reasons that she could not understand.

He said that if the Order had contained no reasons, it would be invalid.

However he said that because Mr Jack had supplied numerous reasons, he had essentially met the condition for making order, and that even if Lady Haldane did not accept most or all his reasons, the Order itself should still stand.

The very act of giving the reasons meant he had "substantially complied", he said.