An Officer Is Charged With Murder. Colleagues Briefly Drop Their Guns.

When England’s prosecution service announced last month that a police officer would be charged with murder after fatally shooting an unarmed Black man in London, the news was met with relief by the dead man’s family.

“We welcome this charging decision, which could not have come too soon,” the family of the man, Chris Kaba, who was killed in September last year, said in a statement. “Now we await the trial of the firearms officer without delay and hope and pray that justice will be served.”

But among the armed police who work for London’s Metropolitan Police Service, known colloquially as the Met, there was consternation. Officers worried that the murder charge signaled a changed attitude toward the use of guns in the course of their duties, the Met police later wrote in a statement.

Within days, hundreds of officers had handed in their weapon permits — known as “blue cards” — and were refusing to carry their guns in protest. The Met was temporarily forced to request support from the army.

The case echoed the ongoing tensions in the United States between the public and the police, and calls for accountability over the deaths of civilians after police encounters.

But it also reflected the unique cultural underpinnings of policing in the United Kingdom, where neither police officers nor the public usually carry firearms.

Some critics in Britain fear that the elite status of the small band of armed officers has afforded them too much power. Earlier this year, the Casey Review, a government-commissioned independent report following the 2021 rape and murder of Sarah Everard by a serving police officer, noted a “deeply troubling, toxic culture” in the Met’s specialist firearms unit, citing “insidious attitudes including misogyny, racism and ableism.”

Supporters, however, say that armed police officers do some of the most dangerous work that exists in law enforcement and deserve more legal protection given the significant risks they face.

The killing of Mr. Kaba, 24, last fall set off protests amid international cases of deadly police violence against Black men. While few details of the case can be disclosed ahead of a criminal trial, investigators noted that a police officer — known only as NX121 — exited a police car and fired a single shot into a car Mr. Kaba was driving, which was believed to be linked to a firearms incident a day earlier. The bullet pierced the car’s windshield and struck Mr. Kaba in the head. Another police vehicle following Mr. Kaba was not marked and did not have its lights flashing, investigators said.

The episode was one of many over the past few decades that have contributed to distrust of the police among Black, Asian and minority ethnic communities in Britain compared with the population at large, experts say.

“Trust absolutely has been on the decline,” said Sarah Charman, a professor of criminology at the University of Portsmouth. The events of recent years were “a perfect storm,” she said, citing the Covid pandemic, a period of financial austerity in which policing budgets were cut and high levels of resignations among officers.

Those factors converged with a number of cases of police criminality, including Ms. Everard’s murder and the conviction of a Met officer this year for sexual violence spanning two decades.

The Casey Review and those scandals “provoked a real sense amongst the public that there is something very wrong in policing at the moment,” Dr. Charman said.

The British policing landscape in which Mr. Kaba was killed is fundamentally different from that of the United States, which has been the scene of so many troubling episodes of deadly police violence, particularly against Black men.

In the United States, 1,201 people were killed by the police last year alone, according to Mapping Police Violence, a nonprofit that tracks deadly police encounters. Nearly all those who died were shot.

In contrast, a total of 1,871 people have died, 80 after being shot, while in or immediately following police custody, in England and Wales, in the more than three decades since 1990.

Even factoring in the difference in population — the United States’ 332 million to Britain’s 67 million — America’s fatality rates are much higher.

But both countries are engaged in a fraught debate over police violence, amid falling public trust in law enforcement and simmering resentment within the ranks of officers, who fear that the decisions they make under enormous pressure could lead to years of legal proceedings.

Armed police in Britain have a particular ability to cause disruption if they protest because so few officers carry firearms — only around 2,400 officers out of the 34,000 in the Met, for instance — and because they carry guns voluntarily. They are entitled to stand down temporarily from their duties if they feel medical, emotional or other life stresses could impact their ability to make critical decisions.

The Casey Review found this had fostered “a widely held view” in the Met’s specialist firearms unit, and across the force, that armed officers “‘need to be allowed’ to bend or break the rules because they are volunteers who could at any point decide not to carry a firearm or ‘hand in their blue card.’”

After firearms officers began handing in their permits last month, the Met’s chief commissioner, Mark Rowley, asked the government to introduce more legal protection for officers who used their weapons.

Suella Braverman, the Conservative home secretary, announced a review of armed policing, arguing that officers “mustn’t fear ending up in the dock for carrying out their duties.”

But rights groups argue that too little is being done to hold police officers to account.

Of the 1,871 deaths since 1990, there have been 11 murder and manslaughter charges against police officers since 1990, and only one conviction, according to Inquest, a British charity with expertise in state-related deaths.

“The suggestion that police officers are less accountable in the eyes of the law than ordinary citizens risks further undermining public trust and confidence,” said Zoe Billingham, a former inspector for the Inspectorate of Constabulary and Fire and Rescue Services, an independent police watchdog group.

England’s policing culture has its roots in the 19th century, when Robert Peel established a centralized force that began patrolling London in 1829. First known as “Peelers” and later “Bobbies” (a nod to their founder), officers wore distinctive blue uniforms, carried batons (known as “truncheons”), handcuffs and whistles.

The force was founded on the principle of “policing by consent” — the idea that law enforcement rests on public cooperation and trust — to differentiate the police from the army, which had been responsible for a number of heavy-handed interventions.

“The arming debate is still a hot potato in the U.K., and it’s something that raises its head regularly,” said Robert Glassborow, a former police sergeant who now lectures in policing at the University of Law. “The hard point is — British policing is about confidence, trust and working together with communities.”

After years of austerity following the 2008 financial crisis and cuts to the number of neighborhood officers, the police have become less visible in communities, which some experts believe has exacerbated an overall decline in trust. Earlier intervention and involvement in the community, rather than just responding to major criminal incidents, would help reduce crime, they say.

“The political commentary recently has focused on the police being too ‘woke,’ and that they should concentrate much more on fighting crime,” said Dr. Charman. “My argument and many other people’s argument has always been, that actually to build up trust and confidence, officers need to be engaging with the public on the ground level.”