Bastards, reptiles, vultures, vermin, sewage in the gutters of the press. If I were a paparazzo I would be keeping my head low today. The cameras that eulogised Diana's every feature, every movement, every activity, will be widely seen as having driven her into a wall. A comet streaked across the sky of public life and entranced the world. Such hysterical fame has reduced many to drink, drugs or suicide. Few have been so literally driven to their deaths.

After the grief comes the yearning for retribution. Nobody nowadays dies by accident. Blame is sovereign lord to every misfortune and demands swift recompense. That appears easily satisfied. The photographers who dogged Diana and Dodi Fayed for the past two months appear to have transgressed all professional constraint. They were insistent, cruel and murderous. With them around, she had no privacy and no dignity. She was imprisoned behind a grille of flashing lenses. In a ghoulish rerun of La Dolce Vita , the lenses leapt from their bikes early on Sunday morning to snap the last, most horrific shot of all.

Yet blame has not done with hunting. Behind the ghouls lie other denizens of this underworld. The editors, picture editors, circulation managers and bosses of the press have driven the market for intrusive pictures ever higher. Diana was simply the hottest property in the history of photography. A handful of fuzzy shots of her and Dodi aboard a yacht off St Tropez, syndicated worldwide, generated at least Pounds 3 million. This put a high price on the couple's heads. But photographers do not set this price. The cry of the freelance down the ages is the same: "I shoot what I see. The boss decides to print."

Having found its target, blame simply demands that "something be done". Yesterday a chorus called for that something. The last minister with responsibility for the media, David Mellor (who decided to do nothing), called for unspecified remedies. Yet behind industries are markets. And markets make less tangible targets. Whenever I hear someone complaining about the press "just trying to sell copies", I wonder who buys these products. Who inhabits this market place, if not readers?

Buying salacious gossip about royals is like drink-driving and tax evasion: it is deplored in others but not in oneself. Yesterday I am sure many a sermon was preached from British pulpits on the avidity of the public for news of the rich and famous. The exorbitant price for the pictures which yesterday's Paris paparazzi were seeking was set by an obsessive worldwide appetite for any news about the lady. If paparazzi are at one end of this sewer, at the other sits a salivating, prurient public. He among us that has no eye for such pictures, let him first cast a stone.

None of this can stem the cry for action. That a public thirsts for intrusion is not reason enough for supplying it. Free markets need regulation. Damage needs redress. There are many products which sections of society may enjoy but which public safety or the rights of individuals cannot allow. For years, British politicians and lawyers have been yearning to get their hands on the press. They now have a case history par excellence . The hounding must stop. It is lethal.

We should note first that the law has acted. The photographers concerned have been arrested. The harassing of motorists at speed and leaving the scene of an accident are crimes in all civilised countries. Trespass, theft and stalking are crimes in most. Chauffeurs of the famous are trained in "burning off pursuit" and probably themselves break the law in doing so. That a law may not have worked in one instance - surely the hardest of all A.P. Herbert's "hard cases" - does not make it a bad law.

However, the implication of interventions from the Foreign Secre tary, from Opposition spokesmen, from Earl Spencer and from others is that Britain now needs a specific law protecting personal privacy, distinct from the laws on trespass, libel and slander. The press will be told that it has not heeded the warnings of successive governments to "put its house in order". The familiar arguments will be taken down and dusted off.

It is now almost ten years since the Calcutt Committee reviewed these arguments. That committee, of which I was a member, shared the view of previous inquiries that a civil law of privacy could not be effective. Such laws exist in France, Germany, Italy and many American states. The French is one of the toughest. Reformers should note where the past month's gross breaches of personal privacy occurred.

All privacy laws tend to be effective in stifling small trespasses but not big ones. Calcutt pondered a graduated list of intrusions that reasonable people might consider fair "in the public interest", a phrase with many devious meanings. Those who are famous for a day, by being involved in accidents or court cases, soon return to obscurity. Some professionals, such as doctors, parsons and academics, appear more vulnerable to intrusion where their private lives infringe the dignity of their profession. Most people feel them fair game.

When we encounter entertainers, sportsmen and lesser politicians, vulnerability moves into the minutiae of private life. A rock star's marriage is regarded by most readers as news, even if it has no "public interest" bearing on his work. Drawing up a law to protect such people would be hard. Harder still is a statute to determine the rights of those who use the glamour of their private lives to promote their public ones. Prime ministers and royalty do this shamelessly.

Most people, which means most juries, would accept that public figures sacrifice some right to privacy by reason of their office. But how much? It is absurd to expect readers to consume only news fed to them by publicists, and not to hear if there is another side of the story. The misfortune of the fortunate has long been the essence of gossip, and gossip the essence of news. How far a newspaper should go is ultimately a matter not of fact, like libel, but of taste. Legislating for taste is notoriously hard. The present self-regulation may not show results in public - intrusion suppressed is by definition intrusion avoided - but I believe it to be the only feasible course.

Times Recommends

• We must lead the world to stability
• The recession's a blessing in disguise
• The guilty men who sent mum to Iceland