LONDON — In Bristol, an English college town where the pubs are usually packed with students, there were fiery clashes between police and protesters. In Kassel, a German city known for its ambitious contemporary art festival, the police unleashed pepper spray and water cannons on anti-lockdown marchers.
A year after European leaders ordered people into their homes to curb a deadly pandemic, thousands are pouring into streets and squares. Often, they are met by batons and shields, raising questions about the tactics and role of police in societies where personal liberties have already given way to public health concerns.
From Spain and Denmark to Austria and Romania, frustrated people are lashing out at the restrictions on their daily lives. With much of Europe facing a third wave of infections that could keep these stifling lockdowns in place weeks or even months longer, analysts warn that tensions on the streets are likely to escalate.
In Britain, where the rapid pace of vaccinations has raised hopes for a faster opening of the economy than the government is willing to countenance, frustration over recent police conduct has swelled into a national debate over the legitimacy of the police — one that carries distant echoes of the Black Lives Matter movement in the United States.
“What we’re seeing is a growing level of discontent among members of our society who see a fundamental illegitimacy in law enforcement under the pandemic,” said Clifford Stott, a professor of social psychology at Keele University and an expert in crowd behavior. “And it has created strange bedfellows.”
Right-wing politicians who bridle at lockdown restrictions are as angry as the left-wing climate protesters who regularly clog Trafalgar Square in London as part of the Extinction Rebellion demonstrations. The traffic snarls from those protests were one of the reasons the authorities pushed for greater powers to restrict such gatherings.
Adding to the sense of outrage is the case of Sarah Everard, a 33-year-old woman who was abducted and killed, allegedly by a police officer, while walking home in London. The Metropolitan Police then roughly broke up a vigil for Ms. Everard on the grounds that the participants were violating coronavirus rules on social distancing.
The potential for more such confrontations is high, Mr. Stott said, citing “the warmer weather, duration of the lockdown and increasing dissatisfaction among sections of the community about the imposition of control measures.”
In Bristol, the trigger for the clashes was sweeping new legislation that would empower the police to sharply restrict demonstrations. A peaceful “Kill the Bill” rally on the city’s College Green turned violent when some of the demonstrators marched to a nearby police station and began hurling fireworks and projectiles at police officers.
The mayor of Bristol, Marvin Rees, harshly criticized the violence, blaming much of it on outsider agitators who he said seized on a peaceful demonstration as an excuse to pick a fight with the establishment.
But Mr. Rees, a Labour Party politician, also staunchly opposes the legislation. He said it was rushed and ill-considered — a cynical bid by a Conservative-led government to “rally their base behind law and order” during a pandemic.
“You can’t police yourself to peace,” said Mr. Rees, adding that he tried to engage Bristol’s police on issues like housing, drug addiction and joblessness. “By the time it comes down to an enforcement issue,” he said, “you’ve already failed.”
The violent clashes in Bristol, which left two police vans charred and 20 officers injured — one with a punctured lung — are deeply frustrating to Mr. Rees, who is the son of a Jamaican father and an English mother.
Last summer, his city became a powerful symbol of the global spread of the Black Lives Matter movement, when a crowd pulled down the statue of a 17th century slave trader, Edward Colston, and dumped it into Bristol Harbor.
This time, however, he fears that the images of shattered windows and burned police vehicles will help Prime Minister Boris Johnson pass the police law, which has already cleared two key hurdles in Parliament.
“The consequences of what they’ve done is to increase the likelihood of that bill winning support,” Mr. Rees said.
For many in Britain, that would be a bitter irony, given that the pandemic has already led to the greatest restriction of civil liberties in recent memory. Coronavirus regulations that were expected to last no more than a few months have now been in place for a year, causing tensions between police and the public not just at protests, but also at house parties and even with those meeting outside for coffee.
Early in the pandemic, one local police force used drones to shame a couple walking a dog on a lonely path. The owners of gyms and sports clubs were raided by police when they opened against the regulations.
An earlier version of the government’s coronavirus regulations contained a provision that allowed nonviolent protests. But that was removed from a later version, leaving the right to peaceful assembly in a kind of legal limbo. Under the latest draft of the rules, issued on Monday, protests would be allowed under limited circumstances, starting next Monday.
These emergency laws were rushed through Parliament without the scrutiny normally applied to legislation. Lacking a written constitution, Britons who want to take to the streets have to rely on the less clear-cut protection of a human rights act.
By contrast, Germany’s Federal Constitutional Court last year upheld the right of its citizens to protest, provided that they adhered to social distancing rules.
“This pandemic has exposed the weaknesses of our unwritten constitution when it comes to certain rights,” said Adam Wagner, a human rights lawyer and expert on the coronavirus rules. “If you take representative democracy from the process of lawmaking, you miss out on key voices.”
The government makes other arguments for the policing bill. Cabinet ministers note, for example, that the security costs of protecting a new high-speed rail link from environmental protesters has been 50 million pounds, or $69 million.
Priti Patel, the home secretary, condemned the clashes in Bristol has “thuggery and disorder” and said protecting the police was the government’s top priority — though not, she added, of some members of the opposition.
“We have been clear that to save lives and fight this pandemic, people must not currently hold large gatherings,” she said in a statement to Parliament. “Too many this weekend selfishly decided that this did not apply to them.”
Further raising the political temperature, the policing bill is moving through Parliament at the same moment as the government’s renewal of its coronavirus regulations, which also drew fire from the libertarian right.
“The Coronavirus Act contains some of the most draconian detention powers in modern British legal history,” said Mark Harper, who chairs the Covid Recovery Group, a caucus of Conservative lawmakers critical of the lockdown rules.
While many say the debate on the role of the police in Britain is overdue, some sympathize with the plight of the officers. They are caught between politicians and the public, with a nebulous constitutional status and a shifting set of rules to enforce, particularly during a public health emergency.
“It’s not the fault of the police that the coronavirus regulations are in part necessarily draconian and in parts unnecessarily draconian,” said Shami Chakrabarti, an expert in civil liberties and a Labour Party politician.
The bigger problem, she said, is that Britain tends to conduct debates about the role of the police after wrenching episodes like a police shooting, the killing of Ms. Everard or the violent clashes in Bristol. This inflames public opinion in one direction or the other, she says, but can get in the way of a thoughtful debate.
“We almost only ever have this discussion in moments of crisis,” Ms. Chakrabarti said, “not in peacetime.”