Local authorities used Regulation of Investigatory Powers Act to follow people, including dog walkers, over five years
Councils were given permission to carry out more than 55,000 days of covert surveillance over five years, including spying on people walking dogs, feeding pigeons and fly-tipping, the Guardian can reveal.
A mass freedom of information request has found 186 local authorities two-thirds of the 283 that responded used the governments Regulation of Investigatory Powers Act (Ripa) to gather evidence via secret listening devices, cameras and private detectives.
Among the detailed examples provided were Midlothian council using the powers to monitor dog barking and Allerdale borough council gathering evidence about who was guilty of feeding pigeons.
Wolverhampton used covert surveillance to check on the sale of dangerous toys and car clocking; Slough to aid an investigation into an illegal puppy farm; and Westminster to crack down on the selling of fireworks to children.
Meanwhile, Lancaster city council used the act, in 2012, for targeted dog fouling enforcement in two hotspots over 11 days.
A spokeswoman pointed out that the law had since changed and Ripa could only now be used if criminal activity was suspected. The permissions for tens of thousands of days were revealed in a huge freedom of information exercise, carried out by the Liberal Democrats. It found that councils then launched 2,800 separate surveillance operations lasting up to 90 days each.
Critics of the spying legislation say the government said it would only be used when absolutely necessary to protect British people from extreme threats.
Brian Paddick, the Lib Dem peer who represents the party on home affairs, said: It is absurd that local authorities are using measures primarily intended for combating terrorism for issues as trivial as a dog barking or the sale of theatre tickets. Spying on the public should be a last resort not an everyday tool.
He argued that the new Investigatory Powers Act, which will take in Ripa powers alongside a raft of new measures, would restrict the ability of local authorities to monitor peoples communications.
But he also said it would give mass surveillance powers to a huge number of government bodies.
As with any legislation, there is a significant risk that authorities will use powers in a way that parliament never intended, added Lord Paddick, calling for proper oversight to ensure any surveillance is targeted and proportionate.