For those who do not know her, Ban Soon-taek is a quiet first lady, married to the secretary general of the United Nations but rarely vocal on global issues. She showed another side, as a champion of human rights equalling her more famous husband, at a recent event on ending female genital mutilation (FGM).

Her ringing call to “end harmful traditional practices and unleash the power of young girls” came on at an event organised in the margins of the UN Commission on the Status of Women in New York on 18 April. She thanked participants for endeavouring to “change a harmful tradition into an empowering mission”.

Mutilation would have been a terrible violation of our daughter's rights

Ban took her inspiration from a meeting organised by the Guardian between her husband and the young British anti-FGM activist Fahma Mohamad two years before in London. She paid tribute to this newspaper’s contributions, expressing hope that the media would continue to “help us spread the message that girls need education, not mutilation”.

As chair of the event, I listened with great interest as Ban spoke about how Fahma was reaching out to address risks to Diaspora communities in developed countries where most people are unaware that FGM is a threat. Her efforts mirror those of my own organisation, Finally Girls Matter, which I founded along with my daughter to protect women and girls of all ages and in all places – including in societies where the practice is largely ignored.

We feel this issue acutely because we come from a community in Mali where FGM is all-too-common. Thirty-three years ago, my husband and I refused to cut our own daughter. This was not easy in a society where men had multiple wives and women had few rights. We refused to buy the idea that the only way to make a girl “clean” and “pure” was to mutilate her genitals. Gazing at our beautiful baby daughter, we knew she was perfectly “clean” and “pure” on the day she was born, and that mutilation would only be a terrible violation of her rights.

We won that difficult battle – but little did we know it would only be the beginning. Decades later, as we prepared to welcome our first granddaughter into the world in the US, the spectre of mutilation returned.

It was time to refuse again, only this time in New York city. With so little understanding of Malian customs, we found ourselves mired in the legal system, and overwhelmed with legal fees, just trying to explain the stakes as our then-son-in-law prepared to advance his gruesome plan for our beloved grandchild.

Our modest means were not the only limitation. It was wrenching to testify against loved ones, and put our community under such a harsh spotlight. But we could never put the reputation of a community above the health of one of its newest members. Nothing would stop us from keeping our granddaughter whole.

This is not a tradition, it is a crime Dr Amale Keita

I testified in the case, which went all the way to the supreme court of the state of New York. After a journey that exhausted us financially and emotionally, the verdict was in. On 31 October 2008, the court took our side, finding that “a substantial risk exists that [the defendant] would circumcise his daughter if given the opportunity”.

The court required supervised access, and our granddaughter was safe.

Years later, she is now old enough to understand why her mother was forced to seek a divorce. After we explained the truth, she asked a question that would dramatically shift our perspective: “What about the others?”

This simple query from a grade-schooler opened our eyes to the larger reality. It was not enough to save one girl – we had to transform our community and help all those at risk around the world.

In this spirit, we founded our new campaign to end FGM. And to seize control of the terminology, we changed the acronym to stand for “Finally Girls Matter”.

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We are grateful to have the support of the secretary general’s wife, the Guardian newspaper, and so many others. That event in New York was our kickoff.

One of the participants, Dr Amale Keita, president and CEO Active Intervention for Mothers, who has personally treated victims, aptly said: “This is not a tradition, it is a crime.”

Let’s work together to end impunity and prevent this crime from every recurring. In that way, we can give communities the best possible resource to build a new future: whole, healthy girls.