The police in London have expressed regret about some of the dozens of protesters they detained on the sidelines of King Charles III’s coronation on Saturday, fueling a national debate about the policing of the event and about the new anti-protest law that officers used in some arrests.
The law, called the Public Order Act 2023, came into effect days before the coronation, giving the police in England and Wales extended powers to detain and charge those they suspect of mounting or of preparing potentially disruptive protests. The ceremony on Saturday was widely seen as the first test for the legislation, which was brought forward last year after a wave of climate protests and had already drawn condemnation from rights groups and legal experts.
The British prime minister, Rishi Sunak, has so far defended both the law and the police, telling broadcasters on Tuesday that his government had simply given officers “the powers that they need to tackle instances of serious disruption to people’s lives.”
“I think that is the right thing to do, and the police will make decisions on when they use those powers,” he added.
But the arrests raised broader questions about a measure that Volker Türk, the United Nations rights chief, had previously described as deeply troubling and incompatible with Britain’s international obligations on freedom of expression and the right to peaceful assembly.
“This law is wholly unnecessary as U.K. police already have the powers to act against violent and disruptive demonstrations,” Mr. Türk said in an April statement.
The coronation security operation was one of the biggest in the history of London’s Metropolitan Police Service, and senior police officials said before the weekend that they welcomed the broadened powers of the new legislation.
Some 64 people were arrested during the operation on Saturday, the police said, including 52 whom officers were concerned would disrupt the event, breach the peace, or “cause a public nuisance,” among other issues.
But by Monday evening, the police had expressed “regret” at the arrest of some anti-monarchy protesters on Saturday, who they said were held because officers suspected they might try to lock themselves in position.
The tactic of “locking on” has been used during a number of recent public demonstrations and is defined in the new legislation as actions that see protesters attach themselves to objects, buildings, or other people. Simply being “equipped for locking on” is now an offense.
The law also makes it an offense to obstruct construction on transportation networks or to interfere with major infrastructure. Many activist groups believe that the legislation fundamentally threatens their right to protest.
Graham Smith, the chief executive of Republic, an anti-monarchy group that staged the largest protest in central London on Saturday, was arrested alongside several fellow activists — despite, he said, talking with the police for months to address potential issues.
Mr. Smith said that the group was seeking legal advice with a view to filing a lawsuit against the police.
The Metropolitan Police have already said that some of those they arrested Saturday morning did not violate any laws. At 6:40 a.m., hours before Republic’s planned demonstration, officers saw people unloading items from a van near the coronation procession route, they said in a statement released Monday night.
The police found placards and “items which at the time they had reasonable grounds to believe could be used as lock-on devices,” according to the statement, and arrested six people “on suspicion of going equipped for locking on.”
The protesters who were arrested said that the devices were in fact luggage straps to fasten banners. After the police investigation failed to prove that anyone had intended to use the straps to lock on, all six had their bail canceled and no further action would be taken against them, the police said.
“We regret that those six people arrested were unable to join the wider group of protesters in Trafalgar Square and elsewhere on the procession route,” the statement added.
Matt Turnbull, one of the activists arrested at the van on Saturday, said that officers visited his home on Monday night to return his phone and offer an apology on behalf of the police service.
“If you’re somebody who is an anti-monarchist, May 6 was the most important day,” Mr. Turnbull said, adding that he would never have done something to jeopardize his right to join a legal protest. But instead of being allowed to demonstrate, he said, he was handcuffed, put in a police van and spent 14 hours in a cell.
“The definition of ‘locking on’ is so broad that the police could detain you for wearing a belt,” he said. “How do you determine someone’s intention of what they are going to use it for? It’s a very scary thing.”