When it comes to the letter of the law, a few words can mean the difference between having your rights protected – or not. This is why human rights advocates are celebrating this month: after a worldwide campaign, and many long meetings and legal arguments, the new draft of the international crimes against humanity treaty has lost an outdated definition of gender that could be used to limit protections for women and LGBTIQ people in war.

On 7 June, the International Law Commission – a body of experts set up by the UN in 1947, to help develop and interpret international law – formally recommended this draft for adoption by states. Finally this treaty, which heads to the UN General Assembly later this year, holds the promise of justice for all victims of the world’s worst atrocities.

Previous drafts of this treaty included a definition of gender borrowed from the Rome Statute (which governs the International Criminal Court (ICC)) that isn’t clear on who is protected. It says: “the term ‘gender’ refers to the two sexes, male and female, within the context of society” – overlooking trans and gender non-conforming identities and leaving it open to dangerous interpretation.

Law scholars and the ICC’s own Chief Prosecutor do understand this definition to include LGBTIQ people, and more broadly, women and men persecuted for not following oppressive dress codes, or ‘traditional’ gendered roles. However, the new draft crimes against humanity treaty doesn’t come with an international court – it’s left up to states to implement. And some consersvative governments may try to take advantage of the definition’s opacity and ignore conflict-related gender-based crimes.

The story of this treaty, and its language, is long – as was the process of removing this controversial gender definition from the text. It took immensely coordinated campaigning from rights advocates and lawyers. This is a significant legal victory for women’s and LGBTIQ rights – and three groups that came together to push for the definition’s removal: MADRE and CUNY Law School, where I work, and OutRight Action International.

Under international criminal law, you can’t persecute people based on sexual orientation, gender identity or sex characteristics. But fundamentalists around the world are promulgating fear and justifying discrimination with claims that women and LGBTIQ rights advocates want to impose what they call “gender ideology” – a supposed attack on “natural families”, “feminine values” and the male-or-female binary as the will of God.

At the bottom of these movements is a fear that women will break out of their “traditional roles” as mothers and caretakers, and seek education or employment instead. (As if women can’t do both, while rigid gender roles also have negative consequences for men). Meanwhile, ultra-conservatives are trying to erase LGBTIQ rights altogether, as their very existence challenges their rigid gender narrative.

This is the context in which we mobilised to challenge the opaque gender definition in the crimes against humanity treaty, which the International Law Commission body of experts opened to comments from the UN, national governments and civil society groups last year. At first, our arguments were met with a chilly response from the treaty’s supporters.

Their pushback was simple: the more changes there were to the treaty’s language, they feared, the more likely it would be that fewer states adopt it. This reasoning was familiar: thinking like this has consistently meant that women’s and LGBTIQ rights are deprioritised in conflicts, including sexual and reproductive healthcare in humanitarian crises. In peace talks, the rush to get warring parties to the table too often leads to women’s exclusion.

Can human rights advocates working together make a difference? Just ask Ray Acheson, who led a civil society advocacy coalition that secured a legally-binding provision on gender-based violence in the Arms Trade Treaty. Ray recalls: “At the beginning, we were getting questions [from governments] like, ‘What does gender-based violence have to do with the arms trade? I don’t get the connection.’ By the end, we had a hundred states saying that it had to be in the treaty and it had to be legally binding”.

Similarly, we didn’t give up at that initial chilly response. Instead, we organised a worldwide campaign for the outdated gender definition to be removed or revised. Time was against us: we had to rally states, UN agencies and other civil society groups to make submissions supporting these arguments, and the treaty was only open for comments for one year.

We spent the first six months organising meetings with experts to work out our legal arguments and reasoning. We held seven briefings to receive feedback from representatives of the International Law Commission, governments, and civil society from around the world. We also distributed a toolkit in four languages to support broad civil society input on the treaty’s gender language and other key provisions.

CUNY Law School compiled feedback from these workshops, briefings and consultations, for a submission to the commission that offered a holistic legal analysis and recommendations to either remove or revise the gender definition. We also circulated our arguments and recommendations in five languages for other groups to sign on to.

Ultimately, nearly 600 organisations and academics from more than 100 countries signed our open letter. At least nine other civil society submissions echoed our demands, including from 60 African human rights groups, led by the Southern Africa Litigation Center; 12 transgender rights groups; two intersex rights groups; and Human Rights Watch.

Moreover, 19 governments affirmed that the rights of women and LGBTIQ people are protected under international criminal law and said this treaty must reflect that. No state spoke against gender rights in the treaty process. An astounding 24 UN special rapporteurs and other experts signed another submission echoing our legal reasoning.

The result, this month, was a final draft of the crimes against humanity treaty from the International Law Commission that removes the outdated gender definition, citing our arguments. Though our campaign isn’t over. Next, the treaty goes to the UN General Assembly this autumn, where states will again debate its language and decide its fate.

Whether it becomes law or not, this is clear: history will remember that all of us working together can make a difference, because all of us have rights that must be protected.