In March, a supply teacher from Birmingham won the right to have her DNA sample, fingerprints, and photograph, taken by police, destroyed. Ms Jones had committed no crime but like many others her details were retained on police records. As DNA sampling becomes the police force's panacea Mark Johnson asks whether it is Britain's criminals or her innocent citizens who now have something to fear.

Ms Jones, a supply teacher from Birmingham, had already suffered a terrible ordeal. Her nerves were shattered after being arrested for hitting an 8-year-old pupil. The CPS decided not to prosecute. Relief. Then came another blow. She was forced to remain at the police station, pose for a photograph, give fingerprints, and open wide for a mouth swabbed DNA sample. "I'm innocent", she protested. "It doesn't matter", they said.

It took Philipa Jones 9 months and a high court ruling to force the police to destroy her DNA sample. It wasn't destroyed because taking DNA from innocent people is illegal, but simply because the police had got their timeline wrong. She won her case on a legal technicality and not because the Lords' ethical sensibilities had been pricked.

The Criminal Justice Act 2003 gave police officers the power to take fingerprints and DNA samples from any arrested person detained at a police station. Previously the suspect needed to be charged first or have been arrested for an offence in which DNA testing could be used. Any suspect refusing to provide this information can now be held down and physically forced to submit their DNA. Say "ahhhh" - thanks for the genetic blueprint.

This law means that just about any person, innocent or not, caught up in the ever revolving wheels of justice will be compelled to provide a DNA sample. And that DNA will be retained forever on the National DNA Database (NDNAD). At the last count in March 2005 the database held over 3 million DNA profiles, the largest collection in the world. And the figure is set to rise to a projected 4.2 million by 2008. Currently 5.2% of the UK population is recorded on the database compared with only 0.5% in the USA.

One need only have been arrested not charged, cautioned, or convicted for DNA to be forcibly taken and retained. Innocent and guilty are no different in the eyes of the law. The database now contains the genetic information of over 140,000 innocent people, 24,000 of whom are children. In Britain, the political progeny of Fox and Mill, we are the only nation on earth to retain the DNA of innocent citizens. Did we not expound the dictum innocent until proven guilty? Maybe that was someone else.

This blurring of the distinction between who can and cannot be groped by the hand of the law was exacerbated by the Serious Organised Crime and Police Act 2005 which empowered police officers to make arrests for any offence. With the statutory restriction on police powers distinguishing between arrestable and non-arrestable offences now removed the police have jurisdiction to arrest and swab just about anyone. "Are you busking without a licence sir? A bit of DNA I think lad." "Speeding were you sir? Come on open wide." "Dropping litter is it eh? Yes, let's have some genetic information." I think you get the picture.

Of course there must be some practical justification for all this, why would the police want everyone's DNA unless they felt confident it would make our society a safer one in which to live? There can be no doubt that since the government's DNA Expansion Programme began in 1999/2000 the number of DNA detections have increased. Figures show a rise from 8,612 detections in 1999/2000 to 21,098 in 2002/3, and 19,873 in 2004/5. A Home office report of January this year estimated that since the law on retention of DNA was changed around 198,000 profiles that would have been destroyed were saved and from these 7,591 DNA profiles were matched with crime scenes. The government will claim these figures show that taking and retaining DNA helps fight crime.

There is a problem though. None of these figures tell us whether the matches led to convictions, in two-thirds of cases they don't. Nor do they tell us whether the matches came from 'future crimes' (DNA retained and then matched to a future crime scene) or 'cold hits' (DNA retained and matched to a past crime) both of which are crucial indicators. The fact is that around 100,000 people (by the government's own admission) commit the majority of crime in this country - they have already been convicted and their DNA retained. It is the vast increase in DNA sampling taken from crime scenes, not from innocent people that has led to the increase in crime detection.

All these figures then seem quite confusing. And they are. Nobody really knows whether arresting everyone and taking their DNA has reduced crime or not. What is clear is that crime detection using DNA reached a peak in 2002/3. It is only after this point that police have been allowed to arrest almost anyone and take DNA from everyone. Yet neither of these things have increased the number of convictions based on DNA profiles - this remains steady at around 0.35% of all crimes for the past three years. The link therefore between taking the DNA of unconvicted people and solving more crime is weak.

Many will argue anyway that they do not have a problem with the police taking their DNA. 'It's only DNA' they will say 'what do I really care?' Or some comment such as 'well if you've got nothing to hide then you've got nothing to fear.' Quite.

But of course many people do have a problem with a regime that forces innocent people to hand over the blueprints to their being. Privacy is at the very core of a free and democratic society and if as individuals we no longer have the right to privacy, the right that we and we alone should know what is most fundamental to us, then the bedrock of our belief system rests on shaky ground indeed. As Baroness Hale of Richmond recently told the House of Lords, "No surveillance technology is more threatening to privacy than that designed to unlock the information contained in human genes."

Moreover the idea that the police should take DNA from everyone they arrest, regardless of whether that DNA will solve the crime they have been arrested for, implies that we are all suspects for every crime past, present, and future. As John Wadham, then director of Liberty, pointed out in 2002, people on the database are primarily designated as suspects and not citizens.

Ultimately then this is a question about what our society is and who its citizens are. Those who argue for the individual's right to privacy have no single point that can trump the perceived protection that retaining DNA samples provides. If I argue for my right to privacy many more will argue their right to safety. The best I can do is to relate my desire for privacy to the identity of the democracy in which I live - there are natural limits to the state's interference in the individual's life. But many will say that providing DNA is a small price to pay for bringing criminals to justice, and right now they have the government and the police on their side. I might consider protesting but, well, I wouldn't want to take the risk.