LONDON — Panning out over scenic hills and lush green fields, the drone zooms in on six parked cars and a truck and flashes a stern message: “These vehicles should not be here.”
Next to be shamed is a couple walking a dog on a lonely path. Captured on the film, released by the Derbyshire police, their stroll is judged “not essential” and therefore in breach of British social distancing rules.
Just weeks ago, Prime Minister Boris Johnson seemed genuinely shocked at the suggestion that the police should enforce a coronavirus lockdown in Britain.
But that was before he introduced the most stringent restrictions in recent memory and instructed the authorities to enforce them.
Some police officers have done so with such gusto that a ferocious debate is underway about the balance between collective responsibility and individual liberty.
Few doubt the need for extraordinary measures to prevent the spread of an illness that has already claimed at least 1,789 lives in Britain and infected thousands more, including Mr. Johnson himself.
But many Britons, who pride themselves on their history of resisting totalitarianism in World War II, do not take kindly to being told off for going for a drive or sitting on a bench in a park.
Nor do small stores like being instructed that they should not sell chocolate Easter eggs because they are “nonessential” items.
Jonathan Sumption, a former Supreme Court judge, offered praise on Monday for the work of many police forces but also expressed alarm at some overly zealous enforcement.
“In some parts of the country, the police have been trying to stop people from doing things like traveling to take exercise in the open country, which are not contrary to the regulations, simply because ministers have said they would prefer us not to,” he told the BBC. “The police have no power to enforce ministers’ preferences, only legal regulations.”
The behavior of the Derbyshire police was, he said, “frankly disgraceful,” adding: “This is what a police state is like.”
Others have questioned whether there has been enough scrutiny of government emergency powers that were rushed through Parliament last week before lawmakers went on vacation.
The police have many supporters, of course. One opposition lawmaker, Barry Sheerman, described them on Twitter as “professional sensitive & sensible in most situations.”
But several incidents have touched a nerve in a nation where individual liberty is taken seriously.
In the past, attempts by governments to introduce national identity cards have failed largely because the idea of the police demanding to see such documents is regarded as alien to the country’s storied historical traditions.
Five years ago, Britons celebrated with much fanfare the 800th anniversary of the signing of Magna Carta, a document that began the long process of proscribing the powers of the monarch.
Britons may be hazy about its contents — hence the joke once made by Tony Hancock: “Does Magna Carta mean nothing to you? Did she die in vain?” — but they know it became a symbol of the preservation of fundamental freedoms.
And to some, those are being trampled even if the rules in Britain are much less exacting than those imposed in several countries in continental Europe.
Those who can work from home are encouraged — but not forced — to do so, and everyone is allowed to leave the house to shop for necessities or for exercise. Unlike in France, for example, Britons do not have to fill out paperwork to go outside.
Stephen Kinnock, an opposition lawmaker, thought he was observing the rules when he posted a picture on Twitter of restrained celebrations on the 78th birthday of his father, Neil Kinnock, a former leader of the Labour Party. The meeting was outside, the men separated by a good distance.
But the South Wales police disagreed and chastised him publicly as making a nonessential journey.
In such situations, much relies on common sense and judgment. But circumstances have also left room for confusion, which is sometimes exacerbated by the government.
For example, the transport secretary, Grant Shapps, suggested on Tuesday that people should try to shop only once a week, though that is not part of official advice.
Colm O’Cinneide, professor of human rights law at University College, London, said that in some cases the police might be responding to political signals rather than the letter of the regulations.
Another complication is that because Britain has a decentralized police force, rules can be interpreted in different ways in different regions. (Police chiefs have tried of late to try to ensure that enforcement is more uniform across the country).
But Mr. O’Cinneide said that cultural factors have come into play, too. There has been a general understanding in Britain that the public authorities and the police need to have a clear legal basis on which to act.
“If they don’t have a specific need for those powers, there is a broad resistance to giving it to them,” he said. “That is part of a cultural tradition.”
The speed of the introduction of the rules may also have contributed to the backlash. Mr. Johnson’s writings as a journalist reflected a strong streak of libertarianism, and, in the early days of the crisis, he was reluctant to restrict personal freedoms.
But his sudden pivot to adopting strong measures has left the authorities scrambling to react.
Citizens had an adjustment to make, too. Policing in Britain has generally had more of a light touch than it has in other European nations. There is no paramilitary police force — like the carabinieri in Italy — and British police officers are not routinely armed.
But, as Mr. O’Cinneide said, “it is difficult to have much community policing when it is enforced by drones.”
The Derbyshire police on Tuesday defended their actions, and the chief constable, Peter Goodman, told the BBC that the drone was deployed after food stores in villages were emptied and picturesque spots were inundated with sightseers.
“Some forces will be doing not enough, perhaps, some forces have probably gone a bit too far and some sit in the middle,” he said. “Some would say we in Derbyshire have gone too far.
“I genuinely believe that we haven’t, because we are trying to do everything through conversation and explanation.”
But Mr. Goodman’s force came in for further criticism after it placed black dye in a pool at a disused quarry in order to discourage people from gathering there to swim.
Despite its attractive cobalt color, the water in what is known locally as the Blue Lagoon is toxic (with a pH of 11.3, almost identical with ammonia). It is dyed regularly to deter swimmers, the police say.