Some might consider it rude and rash to dismiss a ruling by a senior judge, who has served for over twenty years, as drooling idiocy — but it’s hard to think of many more appropriate descriptions. Yesterday, Lady Dorrian, the Lord Justice Clerk and President of the Second Division of the Inner House of the Court of Session, ruled that according to the Equality Act (2010), men become women on receipt of a gender recognition certificate (GRC).

Lesbian meet-ups will be obliged to pretend that a GRC can magically change sex

This means that any man who goes through the necessary steps to obtain a piece of paper from the state is likely to be entitled to enter what were once women-only spaces and services. An exception legitimising exclusion if it is proportionate will stay, but women-only support groups, lesbian meet-ups and those running programmes designed to boost female representation will be legally obliged to pretend that a GRC can magically change an individual’s sex. Most worryingly, because the interpretation of the Equality Act has been made by a senior court, it will be understood as the default. According to some legal experts, because the ruling has been passed by the Inner House of the Court of Session, although it isn’t strictly binding within England, it is likely to apply across the whole of the UK.

The judgment was the conclusion of an appeal brought by the group For Women Scotland (FWS) against Scottish Ministers. Representatives of the Scottish government argued that a law mandating “gender balance” on the boards of public companies ought to include men who identify as transwomen if they have a GRC. As a FWS spokeswoman told me:

It seems almost unbelievable that laws designed to protect women and our unique experience of inequalities now say that “woman” is little more than a state issued certificate held by men … We do have the possibility of appealing to the Supreme Court and will be talking about it with our legal team.

The details might sound dry, but the tremors from this judicial decision have the potential to rock the union itself. At present, the Scottish government is being taken to judicial review over plans to introduce a system of gender self-identification. For the first time since devolution, Scottish Secretary Alister Jack blocked the proposed Gender Recognition Reform bill using a Section 35 order. The UK government argued it would have “an adverse impact on the operation of Great Britain-wide equalities legislation”.

Legal scholar Dr Michael Foran is clear that yesterday’s ruling could strengthen the position of the UK government:

This case clarifies that a GRC is unequivocally not a mere administrative document. Possession of a GRC has wide ranging consequences under the Act. It is therefore increasingly likely that a court will conclude that a Scottish bill seeking to dramatically modify who can obtain one of these certificates does modify the operation of the Equality Act and therefore may engage s.35.

When debating gender self-identification proposals last year, Deputy First Minister Shona Robison confidently asserted, “There is no evidence that predatory and abusive men have ever had to pretend to be anything else to carry out abusive and predatory behaviour.” As the recent case of cross-dressing child rapist Andrew Miller attests, Robison was wrong. Compared to joining the priesthood or training as a teacher or doctor, the process of obtaining a GRC is already relatively simple, requiring applicants to show that they have a diagnosis of gender dysphoria and that they have “lived in the acquired gender” for two years (i.e. a change of details on documents). Yet should the changes proposed by the Scottish GRR bill come to pass, even these minimal safeguards will be effectively obliterated. This will impact services across the UK by creating a two-tier system.

There is nonetheless some scope for optimism in yesterday’s ruling, beyond strengthening the British government’s case. A FWS spokeswoman pithily noted, “It is now categorically clear that men without GRCs cannot self-identify into women’s spaces and services and we hope the Scottish Government will take immediate steps to ensure this is upheld.”

Perhaps the most high-profile man to have a position in a service reserved for women, despite being open about not having a GRC, is chief executive of Edinburgh Rape Crisis Mridul Wadhwa. Be it intentional or not, Lady Dorrain’s judgment could see men like Wadhwa booted from women-only spaces and jobs.

Ultimately, despite the madness of finding that a piece of paper can override biology, sanity can be glimpsed in the ruling. Not only will it benefit the UK government’s legal argument for the blocking of the Scottish GRR, the judgment could finally offer service providers the legal backing to stop gender self-identification into single-sex spaces.