I meet a lot of nice, intelligent people these days who say they aren't aware that their lives have become any less free. Maybe your life is unaffected, I say, but a lot of people are now experiencing Labour's authoritarian laws. Then I choose a story such as this one from yesterday's papers about the artist and photographer Reuben Powell who was arrested and held for five hours under terrorist laws.

I point out that Reuben, who was photographing the old HMSO print works in London, was doing nothing wrong but he had everything to fear from the police who treated him like a criminal, fingerprinted him and took his DNA. But for the action of Simon Hughes MP, a member of the one party that seems to understand the threat we face from the police state – the Liberal Democrats – Mr Powell would have spent a lot more time in custody.

I would add that this is a far from unique event in Britain. I have it on the authority of a policeman of my acquaintance that most of the stop and searches under terrorist laws are inspired by the need for local police commands to meet targets each week, which means that the public is being needlessly harassed while no significant gain against the terrorists is being achieved. In the case of Reuben, the police had only to ask themselves if the former HMSO print works were a likely terrorist target and if a terrorist on reconnaissance would be carrying sketch pad, rubber and craft knife for sharpening pencils.

Oh but this is just a one off, they say. Well, actually it isn't. Photographers, artists, naturalists, trainspotters, journalists are being routinely harassed and persecuted up and down the country. Today, there are reports of a Tory MP, Andrew Pelling, who was arrested while taking photographs of a cycle path. People's fundamental rights are being eroded and nobody seems to give a damn.

Except Norman Baker, another Liberal Democrat MP, who has discovered that the Prevention of Terrorism Act 2004 has been used to stop a staggering 62,584 people at railway stations, while a further 87,000 were stopped by police under rules which allow them to ask people to account for themselves. (What nonsense it is for the government to continue to insist that ID cards will never be demanded on the street.)

Among those most frequently stopped are trainspotters. A 15-year-old boy in school uniform was accosted last year and made to sign a form under Section 44 of the anti-terror act. (Plainly part of any New Labour's modernised tyranny is form filling. We have form 27 of the Violent Crime Reduction Act which is being issued to football fans, form 696 required by the police for those staging live events in London, and this week we had first sight of the 53 questions to be issued to all people travelling abroad.

It seems that anyone who takes a picture in a public is at risk of prosecution and harassment. A Polish man who photographed a woman who was "ill" outside an Edinburgh pub was fined £100 under public order laws and told by the sheriff that he was "unchivalrous". Maybe, but he was hardly a threat to public order. Perhaps that sheriff needs to be sent on a course to learn about Britain's fundamental rights.

More serious, perhaps, is an incident which took place outside the Greek embassy last month when two press photographers were prevented from covering a demonstration. Police removed them from the scene and grabbed one camera. Happily this was filmed and a complaint has now been formally lodged.

However many examples one produces of the slow deterioration of our national life, the erosion of our freedoms and the loss of respect between authority and public, nice intelligent people shrug their shoulders and say the police are just trying to do their job, and we don't live in a perfect world. This is the ultimate complacency, and it derives from a failure to understand that a system of rights can only work if it is universally applied. That is to say that we must are all feel outrage when someone is arrested unfairly and prevented from doing his or her job, even if it's just a bloke taking pictures for his art.

The Guardian is the media partner for The Convention on Modern Liberty, taking place on Saturday February 28 2009, which will debate these and other issues. You can buy tickets here