“Black lives matter” was the slogan chanted last July at a demonstration against police violence in Paris. While the world’s eyes were on the US, where two black men, Alton Sterling and Philando Castile, had been killed by white police officers, thousands gathered in the French capital to protest about the death of Adama Traoré, a 24-year-old Frenchman who suffocated after being arrested by gendarmes during an identity check.

In recent weeks, another young man from a Paris banlieue has made the headlines. It’s alleged that on 2 February in Aulnay-sous-Bois, Théo Luhaka, 22, attempted to intervene when a friend of his was the victim of a violent identity check. Officers allegedly punched and spat at him, subjected him to racist insults and pushed a baton into his rectum. Despite his condition and the fact that he had committed no crime, Luhaka was taken to the police station. But he woke up in a hospital, where a doctor discovered a 10cm-long wound in his rectum and gave him 60 days’ sick leave.

It feels as if French society is suddenly discovering the banal cruelty of police brutality, although such allegations come as no surprise to those who live in the country’s poorer neighbourhoods. From Rodney King to Michael Brown, victims of racism by American police appear regularly in French media. But similar events in France are not given much coverage – and when they are, the racial aspect isn’t mentioned. Social networks, however, are challenging this. Hashtag activism has proclaimed what the media has struggled to make obvious: Traoré and Luhaka are black.

Studies by the NGO Action by Christians for the Abolition of Torture show that each year in France 10 to 15 people die following police action. Typically these are young men of black or north African origin, living in disadvantaged neighbourhoods.

The anthropologist Didier Fassin has revealed the gulf between the police and citizens of poor neighbourhoods: 80% of police officers are from rural areas or provincial towns, where the socio-ethnic makeup is radically different.

According to the Défenseur des Droits (Defender of Rights, responsible for protecting citizens from official discrimination), young men perceived as Arab or black are 20 times more likely to have their identities checked. Abusive identity checks feel like a permanent injustice and are often what sets off unrest.

After the Luhaka scandal, several demonstrations ended in violence. At a rally outside the court in Bobigny and at high school blockades in Paris, the initial calm gave way to rage reminiscent of the protests in Ferguson in the US.

The far right is seizing the opportunity to score points in the presidential campaign. The Front National launched a petition to support the police and its leader, Marine Le Pen, has refused to condemn police behaviour.

President François Hollande visited Luhaka in hospital, probably in an attempt to prevent poorer neighbourhoods being set ablaze. The threat of unrest looms large, with memories of the 2005 riots not far away. Zyed Benna and Bouna Traoré, two teenagers who had done nothing wrong, were chased by police officers, hid in an electrical substation and were electrocuted. An unprecedented wave of unrest shook France for three weeks.

In 2016 the UN committee against torture expressed its concern about “allegations of excessive use of force by the police and the gendarmerie, which has in some instances led to serious injuries or death”. In 1999 the so-called country of human rights was convicted of torture after police subjected a young man of north African heritage to a “particularly cruel and serious” assault.

But these condemnations have not led to a reassessment of police practices, and in most cases impunity remains the rule.

Ultimately, there is a deep-rooted problem that plagues France’s police forces: systemic racism that is neither recognised nor addressed.