The name of Rita Marshall may not mean much to the general public, but it means a lot to me. Unwittingly - we never met - she taught me an early lesson about how journalists ought to behave, and why they so rarely do. It is a lesson that is as much about human relations as it is about media behaviour, and there is a good argument for reviving it.

Rita, who died last week after a lifetime spent on newspapers, including this one (her obituary is on page 66), began her Fleet Street reporting career working for Lord Beaverbrook on the old Daily Express, then a broadsheet paper with a reputation for tough investigation; I followed in her footsteps a few years afterwards, and found myself one week assigned the grim task of interviewing the relatives of murder victims. The idea was to bolster the latest campaign of the Express to bring back hanging in Britain (“String 'em up, it's the only language they understand” was the working slogan).

The job meant tramping up dark streets, knocking on unforgiving doors, attempting to persuade bruised and wary families to revive the kind of memories they had no wish to dredge up again. On more than one occasion, however, to my amazement and relief, I was welcomed in. As soon as I announced I was from the Express, the door swung open. My passport, it emerged, was Rita. She had been the reporter assigned to cover the murder at the time, and, although that had meant her intruding on private grief, she had done so with such tact and sympathy that the people she dealt with remembered her with affection. One mother of a murdered girl told me that she and Rita still exchanged Christmas cards.

I checked with my news editor, a burly northerner for whom no reporter's foot was properly in use unless it was wedged in a door, and he endorsed the Marshall approach. “Whenever you leave a house, leave them wanting you back again,” he said, before ticking me off for failing to spend the night standing outside a house where some local politician's mistress was alleged to live.

I doubt if such delicacy is part of the standard training of today's young reporters. Too many I have spoken to tell of harsh instructions to bring back the story, whatever the cost, and find their performance judged not so much by their reporting skills as by the pressure they have exerted to extract information from unwilling sources. Although the code of conduct that governs press behaviour is explicit on a range of issues from breach of privacy to deception and intrusion, it seems often like a hazard to be negotiated rather than a standard to be achieved.

As a consequence, the tally of allegations about the intrusive behaviour of newspapers continues to rise. The Press Complaints Commission last year investigated more than 4,000 complaints by members of the public, a rise of nearly a third over the previous year, and though it was boosted by some notorious cases, such as Heat magazine's tasteless sticker of Katie Price's disabled son, and several articles involving the McCanns' search for their daughter Madeleine in Portugal, the total for 2007 (the full report comes out later this year) was still at a record high.

Reading through the PCC's annual reports is a depressing experience. The picture that emerges is of a media that all too often wins its case on a technicality, or loses it with a dismissive shrug of the shoulders. A newspaper agrees to run a letter of correction after an inaccurate story, then simply fails to run the agreed text, substituting its own version instead. A team of reporters argues that hanging around outside a celebrity's house for three days in order to get a picture of a new-born baby does not constitute harassment because no one asked them to leave. A Sunday paper lazily repeats an inaccurate story because the warning not to publish it was simply ignored. A confidential informant, revealing a story he considers to be of public interest, finds his cover blown because the newspaper does not consider his information to be confidential after all - he loses his job. The misbehaviour of a 15-year-old is disclosed because, although the law protects the identities of those under 16, the paper simply waits until he is 16 and then runs the story.

Small, grubby misdemeanours, mostly - hardly in the league of the brutal paparazzi who hounded a princess to her death, or reporters illegally tapping into royal phone calls. But these are the encounters that the public are most likely to experience. There are a few encouraging signs; what is noticeable from the most recent cases handled by the PCC is how few involve national newspapers. The majority are brought against provincial papers, celebrity magazines and - I fear - the Scottish red-tops, currently fighting a cut-throat circulation war.

Sir Christopher Meyer, chairman of the PCC, argues that the increase in complaints reflects the commission's greater visibility and the extension of its remit to cover internet material. He says that there is “a growing confidence among the public in what the commission has to offer”. But any study of the cases themselves reveals a routine disregard of what constitutes basic courtesy, and a casual disregard of the industry's own regulations.

The press will never be popular. Unearthing inconvenient facts from those who are seeking to protect their reputations or conceal wrongdoing is not an activity designed to make friends. But when innocent citizens are caught in the crossfire of media investigation, it is ultimately the responsibility of the reporter to remember that the measure of an intrusive inquiry should not just be the depth of tomorrow's headline, but the human being on the receiving end of it.

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