“THIS season there is something at the seaside worse than sharks,” declared a newspaper in 1890. “It is the amateur photographer.” The invention of the handheld camera appalled 19th-century society, as did the “Kodak fiends” who patrolled beaches snapping sunbathers.

More than a century later, amateur photography is once more a troubling issue. Citizens of rich countries have got used to being watched by closed-circuit cameras that guard roads and cities. But as cameras shrink and the cost of storing data plummets, it is individuals who are taking the pictures.

Through a Glass, darkly

Some 10,000 people are already testing a prototype of Google Glass, a miniature computer worn like spectacles (see article). It aims to replicate all the functions of a smartphone in a device perched on a person’s nose. Its flexible frame holds both a camera and a tiny screen, and makes it easy for users to take photos, send messages and search for things online.

Glass may fail, but a wider revolution is under way. In Russia, where insurance fraud is rife, at least 1m cars already have cameras on their dashboards that film the road ahead. Police forces in America are starting to issue officers with video cameras, pinned to their uniforms, which record their interactions with the public. Collar-cams help anxious cat-lovers keep tabs on their wandering pets. Paparazzi have started to use drones to photograph celebrities in their gardens or on yachts. Hobbyists are even devising clever ways to get cameras into space.

Ubiquitous recording can already do a lot of good. Some patients with brain injuries have been given cameras: looking back at images can help them recover their memories. Dash-cams can help resolve insurance claims and encourage people to drive better. Police-cams can discourage criminals from making groundless complaints against police officers and officers from abusing detainees. A British soldier has just been convicted of murdering a wounded Afghan because the act was captured by a colleague’s helmet-camera. Videos showing the line of sight of experienced surgeons and engineers can help train their successors and be used in liability disputes. Lenses linked to computers are reading street-signs and product labels to partially sighted people.

Optimists see broader benefits ahead. Plenty of people carry activity trackers, worn on the wrist or placed in a pocket, to monitor their exercise or sleep patterns; cameras could do the job more effectively, perhaps also spying on their wearers’ diets. “Personal black boxes” might be able to transmit pictures if their owner falls victim to an accident or crime. Tiny cameras trained to recognise faces could become personal digital assistants, making conversations as searchable as documents and e-mails. Already a small band of “life-loggers” squirrel away years of footage into databases of “e-memories”.

Not everybody will be thrilled by these prospects. A perfect digital memory would probably be a pain, preserving unhappy events as well as cherished ones. Suspicious spouses and employers might feel entitled to review it.

The bigger worry is for those in front of the cameras, not behind them. School bullies already use illicit snaps from mobile phones to embarrass their victims. The web throngs with furtive photos of women, snapped in public places. Wearable cameras will make such surreptitious photography easier. And the huge, looming issue is the growing sophistication of face-recognition technologies, which are starting to enable businesses and governments to extract information about individuals by scouring the billions of images online. The combination of cameras everywhere—in bars, on streets, in offices, on people’s heads—with the algorithms run by social networks and other service providers that process stored and published images is a powerful and alarming one. We may not be far from a world in which your movements could be tracked all the time, where a stranger walking down the street can immediately identify exactly who you are.

Sovereign over your own body and mind—and face

This is where one of this newspaper’s strongly held beliefs—that technological progress should generally be welcomed, not feared—runs up against an even deeper impulse, in favour of liberty. Freedom has to include some right to privacy: if every move you make is being chronicled, liberty is curtailed.

One option is to ban devices that seem irksome. The use of dashboard cameras is forbidden in Austria. Drivers who film the road can face a €10,000 ($13,400) fine. But banning devices deprives people of their benefits. Society would do better to develop rules about where and how these technologies can be used, just as it learned to cope with the Kodak fiends.

For the moment, companies are treading carefully. Google has banned the use of face-recognition in apps on Glass and its camera is designed to film only in short bursts. Japanese digital camera-makers ensure their products emit a shutter sound every time a picture is taken. Existing laws to control stalking or harassment can be extended to deal with peeping drones.

Still, as cameras become smaller, more powerful and ubiquitous, new laws may be needed to preserve liberty. Governments should be granted the right to use face-recognition technology only where there is a clear public good (identifying a bank robber for instance). When the would-be identifiers are companies or strangers in the street, the starting-point should be that you have the right not to have your identity automatically revealed. The principle is the same as for personal data. Just as Facebook and Google should be forced to establish high default settings for privacy (which can be reduced at the user’s request), the new cameras and recognition technologies should be regulated so as to let you decide whether you remain anonymous or not.

Silicon Valley emphasises the liberating power of technology—and it is often right. But the freedom that a gadget gives one person can sometimes take away liberty from another. Liberal politicians have been lazy about defending the idea of personal space, especially online. The fight should start now. Otherwise, in the blink of an eye, privacy could be gone.