Women are women. We didn’t need a court to tell us that. But here we are. It took a Supreme Court decision to confirm what we all know: that a piece of paper cannot make a man a woman.

For too long the price has been paid by individual women taking action to uphold the law, at great personal cost.

Just last month, we saw the extraordinary case of a nurse suspended from work for addressing a transgender paedophile as “Mister”. Separately, in East Fife, Sandie Peggie was suspended after she complained about a male doctor who identifies as a woman sharing the same communal changing room. A few weeks ago, I met the Darlington nurses forced to bring legal action after a male nurse started using their changing room. These nurses’ careers are threatened, but the man has the support of the ill-advised hospital managers, who misunderstand the law.

Nonetheless, it is a powerful victory for the determined women behind For Women Scotland (FWS) – and women all over the UK – that the Supreme Court has allowed their appeal. The protection of women’s spaces, services and associations will no longer be undermined by the ability of men to obtain a Gender Recognition Certificate and change the sex on their birth certificate to female.

My worry now is that we have a Labour government that has bent the knee to this ideology. Keir Starmer believes one in one thousand women have penises. No one in the cabinet can define what a woman is. I spent years battling abuse from Labour MPs as I fought to uphold biological sex in government and blocked the SNP from introducing their mad self-identity laws. Yet this Labour government is not interested in bringing sanity and common sense. Instead, right now they are drafting yet more equality laws that will bring even more confusion.

We shouldn’t need an Equality Act, workplace regulations and endless court cases to recognise that women need single sex changing rooms and toilets. As the charity Sex Matters point out, the two most common sexual offences are indecent exposure and voyeurism. A subset of men will go to extreme lengths to prey on women who need protection. Sadly, a raft of foolish guidelines designed to signal organisational inclusivity with little understanding of the law have been embedded across the private and public sectors.

That is why, although I welcome today’s judgment, I know too many organisations will still fail women. As Minister for Women and Equalities, I started a call for evidence to find such examples of bad guidance that is misinterpreting the law. The results were depressing. The Government needs to continue my work and ensure the dignity, privacy and safety of women and girls is protected.

Litigation is stressful, costly and time consuming. It is time for the government to stop relying on brave women to do their job. Health Secretary Wes Streeting says he is on the side of the Darlington nurses, but is prevaricating in the hope that this judgement will clear up any ambiguity. But it is already clear that single sex changing rooms for women in workplaces are not just permitted, but required by law.

Outrageously, in the Darlington and East Fife cases, the union that is supposed to represent nurses, the Royal College of Nurses, refused to represent the female nurses or provide legal assistance, instead saying it was “unwavering in our commitment to end transphobia in nursing”.

It’s hard to believe that with all the challenges facing the nursing profession in this country, promotion of contested and damaging ideology can be a priority. But sadly this is a pattern we have seen across the public sector. Professor Alice Sullivan’s recent report into data and research in sex and gender spells out why in healthcare in particular, using confusing terminology threatens not just the privacy and safety of women staff and patients, but can put lives at risk.

Now that we have legal clarity on the foundational question of the definition of sex, Keir Starmer should show some courage and do the right thing. And across the government and the public sector, managers must start to recognise that gender ideology is not an act of kindness to a perceived maligned minority. It is a very serious matter that can create risks and cause great discomfort to women and men, and children of both sexes.

The Conservative Party under my leadership is the party of common sense. We will be holding the Government’s feet to the fire so that they do what is necessary, not what is trendy.

Rt Hon Kemi Badenoch MP is leader of the Conservative Party