A sprawling surveillance system – with unprecedented reach into private lives, even private thoughts – is being summoned up from computers and smartphones. It is almost three years since Edward Snowden gave the world the facts. As the tale has turned and twisted since, the pry-masters have insisted that the innocent have nothing to fear, and that everything is done with rigorous checks. But if one moral has run right through the story, it is that soothing whispers of sweet reason should be received with deep scepticism.

The investigatory powers bill, published on Tuesday, illustrates why. It is, in its way, a triumph for Snowden: it involves the British security state coming clean about the extraordinary existing facility to snoop that he exposed, spelling the powers out in statute for the first time. Ahead of its publication the reassuring talk was of the exceptional parliamentary scrutiny that it had gone through, and the 122 tweaks and safeguards that three separate committees had put forward, all carefully considered as the draft law was refined. Yes, there were concessions, such as bowing the knee to reality on what it is feasible to ask of tech companies in relation to encryption. But at the same time, and without any advertisement, some tentacles of surveillance are being licensed to creep further than before.

Communication providers, who were already set to be tasked with keeping exhaustive data on phone calls, social messages and unlawful sites, will now be expected to keep automatically a year of internet connection records – which could include a deeply private browse of, say, the Marie Stopes or Gamblers Anonymous site. Alert citizens may have grown uneasily used to the idea that GCHQ can get its hands on such information, and the police will have the facility too. Knowledge is power, and the number of fallible human beings who possess it – and perhaps misuse or mislay it – could soar. Measures initially advanced to deal with serious criminals will be turned on migrants, with new powers for officials pursuing immigration and nationality offences, and immigrant detention facilities subject to domestic interception.

The stampede to the statute book is claimed necessary because the emergency legislation that licenses much data collection is due to lapse next year. The government dismisses the obvious logical possibility of legislating for a narrow and improved replacement for the Data Retention and Investigatory Powers Act while taking longer to consult and reflect on everything else. An opposition worthy of its name, which Labour sometimes struggles to be, would move beyond the indulgence Andy Burnham showed the home secretary in the autumn, and push hard on this particular point. As it was, he was still insisting on Tuesday that he would not rush to judgment.

For as cars, watches and even white goods acquire connectivity, it will become possible to build up exhaustive logbooks on the lives of others. Bluntly described powers to switch on cameras and microphones on people’s own phones starkly reveal how the tide of technology is washing away all need for the old art of installing bugs, as well as the old practical and procedural limits on their use. In purely technical terms, the depth of the monitoring that the smartphone can enable goes way beyond anything afforded by the electronic tag.

This context – in which one year’s surveillance fiction can become next year’s surveillance fact – is what makes eternal vigilance necessary. The current standoff in the US between Apple and the FBI is increasingly underlining the point. The FBI’s original case was that it was targeting only one terrorist’s phone, but in the days since it has itself revealed far more ambition. Right around the world, technology is steepening the slide from the rare and particular to the routine. Seemingly pinpointed actions can prefigure a smothering blanket.