A man goes out to buy some beer. As he leaves the off-licence, a man lurking in a nearby doorway takes a surreptitious photograph. In the early morning two days later, the police call at his house and charge him with buying alcohol for under-18s. He is told that over the past two weeks he has received twelve letters from local beer and wine suppliers, visited six alcohol-related websites and been seen in conversation with three 17-year-olds later arrested for drunkenness. East Berlin, 1952? No, London - or Liverpool or Nottingham - 2008. The Stasi, East Germany's secret police, was disbanded 19 years ago; but its methods, mindset and powers to intimidate live on in 21st-century Britain.

Thousands of council workers across Britain today routinely authorise and engage in surveillance operations that were the hallmarks of dictatorships a generation ago. Letters are intercepted, conversations overheard, meetings photographed, internet connections monitored and contacts and patterns of behaviour established. All this covert intelligence is gathered not to thwart a bomb plot or break up terrorist cells but to ensure that applicants to a popular school live in the catchment area, to stop dogs fouling the pavement, to catch fly-tippers or prove that a man claiming sickness benefit was moonlighting. With barely a whimper of protest, Britons are being corralled into the kind of supervised society, with all the apparatus of camera surveillance, snooping and bureaucratic controls once seen as the classic instruments of tyranny.

All this has happened with the full - though probably not informed - consent of Parliament. The Regulation of Investigatory Powers Act (Ripa), enacted in 2000, was intended to put on a statutory basis the informal methods used to ferret out evidence of fraud or antisocial behaviour: dropping litter, rogue trading, illegal parking or falsely claiming benefits. The adoption of the European Convention on Human Rights, however, meant that such informal approaches were no longer acceptable and could be challenged in court. And so the new Act was passed, to codify and regulate investigations. As so often, it was accompanied by soothing reassurances that this would stop abuse and uphold individual rights. The very opposite has happened. Once enacted, the law was hugely expanded by ministerial fiat. Surveillance was allowed not only to protect national security or prevent crime, but on the grounds of economic wellbeing, assessing tax, public health, public safety, or, in a chillingly Soviet phrase, “for any purpose ...specified for the purpose of this subsection by an order made by the Secretary of State”.

Little objection was made, because most people do not believe the Home Office to be malign or intent on establishing a one-party state. It also seemed sensible at the time to delegate some powers of investigation to relevant local officials. Fly-tipping, selling counterfeit goods, fouling pavements and cheating taxpayers infuriate voters, who frequently urge their councils to crack down on such abuses. But legislators should beware of the knee-jerk response. Allowing councils to authorise themselves to carry out surveillance - without informing the target or seeking judicial cover - sets a dangerous precedent. This is how freedom is eroded. Dictatorships are upheld not by daily terror but by giving jobsworths petty, unchallenged powers. As we report today, such powers are being used more and more. Last year there were 12,494 applications for “directed surveillance”, almost double the number for 2006.

Already, Britain has more surveillance cameras than any other Western democracy. With shop “loyalty” cards, data banks, phone and internet records and official surveys, our lives are recorded hour by hour. Most people accept this as the price of consumer convenience or social harmony. And most councils do their best to ensure that abuses are prevented by strict guidelines or training staff. But the trend is alarming. When Ripa was passed, MPs assumed they were helping to catch terrorists and hardened criminals. They did not think the powers were to be used to snoop on dog-walkers. We must not, like the Stasi, assume a right to pry into others' lives.