Years before France was inflamed with anger at the police killing of a teenager during a traffic stop, there was the notorious Théo Luhaka case.

Mr. Luhaka, 22, a Black soccer player, was cutting through a known drug-dealing zone in his housing project in a Paris suburb in 2017 when the police swept in to conduct identity checks.

Mr. Luhaka was wrestled to the ground by three police officers, who hit him repeatedly and sprayed tear gas in his face. When it was over, he was bleeding from a four inch tear in his rectum, caused by one of the officers’ expandable batons.

Mr. Luhaka’s housing project, and others around Paris, erupted in fury. He was held up as a symbol of what activists had been denouncing for years: discriminatory policing that violently targets minority youth, particularly in France’s poor areas.

And there was a sense that, this time, something would change. President François Hollande visited Mr. Luhaka in the hospital. Emmanuel Macron, then a presidential candidate in an election he would win months later, pledged to transform the country’s centralized police system into one more tailored to neighborhoods, so that police officers could recognize locals and “rebuild trust.”

That never happened. Instead, the relationship between the country’s minority populations and its heavy-handed police force worsened, many experts say, as evident in the tumultuous aftermath of the killing in late June of Nahel Merzouk, 17, a French citizen of Algerian and Moroccan descent.

After multiple violent, publicized encounters involving the police, a pattern emerged: Each episode led to an outburst of rage and demands for change, followed by a pushback from increasingly powerful police unions and dismissals from the government.

“It’s a repeating cycle, unfortunately,” said Lanna Hollo, a human rights lawyer in Paris who has worked on policing issues for 15 years. “What characterizes France is denial. There is a total denial that there is a structural, systemic problem in the police.”

Calls to overhaul the police go back at least four decades to when thousands of young people of color marched for months in 1983 from Marseille to Paris, over 400 miles, after an officer shot a young community leader of Algerian descent.

Chanting slogans like “the hunt is over,” the marchers demanded changes to police practices that never came. The number of fatal encounters continued to climb.

France is one of the few Western democracies to have a centralized, national police force that answers directly to the interior minister, often referred to as “France’s top cop.” Its 150,000 members are organized in a top-down structure, with a reputation for brutal enforcement methods.

“In France, the police are increasingly at the service of the government, not the citizens,” said Christian Mouhanna, a French sociologist who studies the police.

In the late 1990s, the French government tried to introduce community policing.

The goal was to “regain a foothold in the suburbs by means other than repression” and build a rapport with locals to prevent crime, said Yves Lefebvre, a police union leader who recalled organizing soccer games between residents and officers.

But the new approach was dropped after only a few years. “Organizing a rugby game for the youth in a neighborhood is good, but it’s not the police’s primary mission,” Nicolas Sarkozy, then France’s interior minister, said in 2003. “​​The primary mission of the police? Investigations, arrests and the fight against crime.”

Mr. Sarkozy then introduced a “policy of numbers,” with officers expected to make a certain number of arrests.

But they also fueled calls for more and tougher law enforcement.

“The analysis of the police and interior minister was that if the police had been greater in number, more mobile and better armed, there would not have been riots,” said Sebastian Roché, a policing expert at the country’s National Center for Scientific Research.

Since then, France has passed new laws toughening penalties and expanding police powers almost every year. It extended the use of certain weapons that fire rubber bullets the size of golf balls, which have caused dozens of mutilations and are banned in most European countries.

Fabien Jobard, a political scientist specializing in the police, said this “legislative inflation” was partly aimed at further protecting the police and limiting their accountability.

“It seems that one of the most important tasks of the police is to protect the police,” he said.

The new objectives of tough policing fueled an increase in identity checks, which studies have shown are not effective in identifying criminals and disproportionately target minority youth.

A 2017 investigation by the country’s civil liberties ombudsman found that “young men perceived to be Black or Arab” were 20 times more likely to be checked by the police than the rest of the population. French courts have faulted the government twice for discriminatory police checks.

“They are the backward version of community policing,” Ms. Hollo said.

Éric Henry, the spokesman for Alliance, a major French police union, denied that identity checks were carried out in a discriminatory manner and said that officers were sticking to a legal framework that allows checks of people suspected of criminal activity.

Mr. Henry said the deterioration of the relations between the police and suburban residents stemmed from a rise in crime and a justice system that is not tough enough. “We need to reassert the authority of the state,” he said, calling for the introduction of mandatory minimum sentences for those who attack officers. French authorities said that 800 police officers had been injured in the recent riots.

In the case of Mr. Luhaka, the aftermath of his violent arrest followed a well-worn French playbook. Youths from the neighborhood in Aulnay-sous-Bois, a suburb 30 minutes northeast of Paris, protested by setting cars on fire. His neighbors wore T-shirts emblazoned with “Justice for Théo” and organized a march.

The suburb’s mayor, Bruno Beschizza, a former police officer and union spokesman, said he was shocked and called for building trust between the police and residents. A community group held open discussions and demanded regular sporting events with locals and officers and an end to arrest quotas, among other things.

“Nothing happened,” said Hadama Traoré, a local activist who defined himself as a revolutionary and led the meetings. He was later convicted of threatening the mayor.

Instead, the municipal police force has grown exponentially, becoming the biggest in the area, with 84 officers — four times that of the nearby, more populated Aubervilliers.

Traditionally, the municipal police play an administrative role, handing out parking tickets and traffic fines. In many cities, like Paris, they are unarmed. But in Aulnay-sous-Bois, they are equipped with 9-millimeter guns, tasers and the weapons that fire rubber bullets the size of golf balls.

During the recent riots, more than 100 masked people attacked the municipal police station with fireworks and firebombs. CCTV cameras captured municipal police officers fighting them off with shields and rubber bullets.

Mr. Beschizza said he considered the municipal officers, who answer to him as mayor, to be community police, who often patrol by foot, get to know families and young people, and are instructed to do identity checks “with discernment.”

“I refuse to say there is systemic racism in police because today, there are lots of diverse police officers who come from their neighborhoods themselves,” Mr. Beschizza said from City Hall, where the gates and doors remained barricaded by huge, protective concrete blocks.

The federal authorities, too, have long rebutted accusations of systemic racism within the police force, calling them “totally unfounded.”

But while the Interior Ministry regularly releases statistics on crime, it has repeatedly refused to quantify police checks, let alone break them down according to the racial backgrounds of those they stopped, which is forbidden in France, a country that considers itself colorblind.

“At the same time, as we know very little about identity checks, we know lots about how many cars were burned every night, how many arrests were made, how many public buildings were vandalized,” said Magda Boutros, an assistant sociology professor at the University of Washington in Seattle who specializes in policing in France.

The result, she said, was a narrative portraying the a largely white police force “as an essential tool to control out-of-control youth” in the poor suburbs “while not giving the tools that others might use to question policing practices.”

The few times the government has tried to address accusations of racist policing, it has faced an even greater obstacle: the police unions.

In recent years, during clashes with the Yellow Vest movement — a working-class revolt — as well as more recent protests opposing changes to France’s pension plan, the French government has increasingly relied on the police to control crowds.

That dependence has enabled police unions — a powerful political force elected by nearly 80 percent of all police officers — to secure regular pay increases and, more pointedly, block any change that would limit police powers, experts say.

In 2020, the unions showed the full extent of their power. As outrage over the police killing of George Floyd in the United States spread to France, Christophe Castaner, then the interior minister, proposed disciplinary action against officers suspected of racism.

In response, unions staged a protest on the Champs-Élysées and called on officers to throw down handcuffs in front of police stations across France. “The police are not racist,” said Fabien Vanhemelryck, the leader of the Alliance police union. “We’re tired of hearing that.”

Under pressure, Mr. Castaner met with union leaders, including Mr. Lefebvre, who announced that the interior minister had lost the trust of the police and could no longer represent them. A month later, Mr. Castaner was replaced.

“The president knows that an interior minister who has all the police unions against him can’t stand,” said Mr. Lefebvre, the leader of France’s second-most powerful police union alliance.

Last month, after the police shooting of Mr. Merzouk, Alliance and another police union announced that they were at war with the rioters, whom they deemed “vermins” and “savage hordes.”

Since Mr. Luhaka, now 28, had his own encounter with the police, his injury has been determined to be permanent, and he has been unable to work.

While the officers involved in his arrest received no internal disciplinary sanctions, three of them face criminal charges in a case scheduled for court in January — almost seven years later.

“This trial is super important symbolically,” said Eléonore Luhaka, Mr. Luhaka’s eldest sister. “If the trial is favorable, then it will free many more people to speak out. It will send a message that justice can also be found in poor neighborhoods.”

Juliette Guéron-Gabrielle contributed reporting from Paris and Aulnay-sous-Bois.