Facebook just set a dangerous precedent.

When 23-year old black woman Korryn Gaines broadcast a standoff with police on social media in early August, the police asked Facebook to shut her account down. Facebook complied, and within hours, the police had shot Gaines dead. Her five-year-old, who was also shot, survived.

Gaines was in Baltimore, but racist police violence isn’t just an American problem. A few weeks before Gaines was killed, Liverpool teenager Mzee Mohammed died in police custody -- the latest in a shamefully long line of people from black and minority ethnic communities to die in police custody in the UK.

Social media has become an essential tool in the fight against racist police violence. It allows people to document what’s happening, which both protects them and raises awareness of the epidemic of police violence against black and minority ethnic people.

But if Facebook censors this critical tool at the behest of the police, it will leave those who experience police violence dangerously exposed.

Tell Mark Zuckerberg to explain Facebook’s policy on deactivating accounts at the request of police, and to commit to do more to protect people like Korryn Gaines.

The launch of Facebook live video has put the social media giant in a position of enormous power. It now controls one of the most effective tools the world has for exposing police misconduct. Just last month, the Facebook livestream of Philando Castile’s death at the hands of police in the US sparked protests across America.

But with that power comes responsibility. And if Facebook just complies with police requests to suspend broadcasts and accounts, it will be shielding police misbehavior from the public -- and cutting people off from crucial support networks.

Here in the UK, we desperately need our social media to allow individuals to hold the police to account. If you’ve never heard of Mzee Mohammed -- or Sheku Bayoh, Sarah Reed or Kingsley Burrell -- you’re not alone: the mainstream media routinely fails to report the deaths of black and minority ethnic people in custody or following contact with the police. But there have been more than 1,500 such deaths, disproportionately of black and minority ethnic people, since the 1990s.

Tell Facebook to explain its actions and stop this precedent of censoring user accounts at the request of the police.

Korryn Gaines wanted her standoff with police to be broadcast to her networks. That didn’t happen. But we can make sure that, in future, Facebook refuses to censor the broadcasts of people facing racist police violence -- by getting Facebook to change its policy.

Facebook’s CEO Mark Zuckerberg has gone to great lengths to declare his support for the Movement for Black Lives. He’s made public statements about the need to address systemic racism in the US and last month, he even hung a massive sign of support outside Facebook headquarters. Now we need to pile on the pressure to turn those words into action.

Already over 60,000 Canadian and American SumOfUs members have signed our petitions, and our campaigns have hit the press. If we, in the UK, stand with SumOfUs members globally, we could force Mark Zuckerberg to go beyond words -- and make Facebook change its policy.

If Mark Zuckerberg really cares about racial justice, he’ll take action and stop Facebook’s censorship of crucial video and broadcasting now.