On paper it does not sound like something that would spark nationwide interest. Last week the UK supreme court gave its judgment on a case brought by a women’s group against the Scottish government over the Gender Representation on Public Boards (Scotland) Act 2018.

But its judgment – that the word “woman” in equality law refers only to biological sex – has upended years of legal interpretation. And the news of the ruling led to celebrations, protest and an outpouring of emotion.

For some, such as the Guardian Weekly deputy editor, Isobel Montgomery, who is a trustee of the domestic violence charity Rise, the court’s decision is reassuring. The Brighton charity offers women-only services based on biological sex, as well as separate LGBTQ services.

This, she says, is essential for women who have been subject to male violence and only feel safe if they are in a space with other cis women. “You are dealing with a cohort of people who are in great distress and deserve to be met where their trauma is,” she says.

But for others, such as Ellie Gomersall, an activist for the Scottish Greens who campaigns for trans rights, the judgment is heartbreaking.

“I think this ruling means that, as trans people, it’s now completely impossible for us to ever be able to just put our trans-ness behind us and go about our normal day-to-day lives. It’s always going to be a question for us – are we going to be told: ‘Actually, no, you can’t come in here’?”

The Guardian’s Scotland correspondent, Libby Brooks, explains how the ruling came about and what it could mean. She tells Helen Pidd that some legal experts have explained that this legal ruling means organisations can exclude trans women from women-only facilities – but they’re not obliged to do so.

Yet with the head of the Equalities and Human Rights Commission saying trans people must use toilets that fit their biological sex at birth, and that changing rooms and hospital wards should use the same criteria, it marks a serious change in public life.