The media column - Peter Wilby smells a bad egg

The one-sided coverage since Sion Jenkins was acquitted illustrates the dangers of trial by newspape

The New Statesman was first to suggest that Sion Jenkins, the deputy head convicted in 1998 of killing his foster daughter, might be innocent. The strongest argument for his guilt was the lack of other plausible suspects. The evidence against him always seemed to me inadequate. I was surprised at his conviction and, as editor, welcomed an article immediately after the case from the legal affairs journalist Bob Woffinden. We ran it as a cover story, headlined "Sion Jenkins is innocent".

It was a one-sided article with a one-sided headline. That is what a weekly comment magazine does. But we were not, I think, as one-sided as almost the entire British press has been since Jenkins was acquitted this month after a second retrial in which the jury failed to agree. On the basis of allegations that were never put before a jury - that Jenkins beat his wife and used corporal punishment on his own four children - the papers have, in effect, headlined "Sion Jenkins is guilty". These are unconfirmed allegations largely from a single source: Jenkins's ex-wife, Lois, who gave her full 20,000-word account to the Mail on Sunday. Most papers, including the Guardian, reported them without any hint that it was possible to question them.

The Sunday Telegraph had a piece that Jenkins himself wrote in jail four years ago, but presented it as though it were handling an apologia by Genghis Khan. Jenkins's account, the paper's introduction said, "provides a fascinating insight into his character", and the ubiquitous Dr Theodore Dalrymple was wheeled up to provide a psychiatric assessment that noted "detachment and seeming egocentricity". As for the Sun, it had Jenkins tried, convicted, sentenced, hanged, drawn and quartered in an instant when he declined to take up the paper's offer of a lie-detector test.

I hold no brief for Jenkins, and I was not sufficiently convinced of his innocence to put the NS's full weight behind a campaign on his behalf after Woffinden's article. But press behaviour over the past week illustrates the dangers of trial by newspaper. For the press, an allegation that the accused is a bad egg with a disreputable past is conclusive proof of guilt. So it often is for the police, which explains why they frequently arrest the wrong people. But though some evidence of previous "bad character" has been allowed in court since 2004, the criterion for guilt in a criminal case remains "beyond reasonable doubt", not "he's just the sort wot would have dun it".

Given the opportunity, the press will cast its net very widely indeed. Take Neil Entwistle, the Briton who is being extradited to Massachusetts to face charges of murdering his wife and baby daughter. Suggestions of dubious business activities had already emerged, but the press was troubled by evidence that, at school and university, he had been a "model student" (a description people seem to use only when talking to newspapers). Now the Mail on Sunday alleges an affair, during Entwistle's student years, with the niece of Reggie Kray. Worse, she was allegedly married at the time "to a drug-dealing club doorman" and "wore skimpy tops and miniskirts".

Skimpy tops and miniskirts? Enough said.

The press is now taking Chris Huhne, previously an outsider for the leadership of the Liberal Democrats, seriously. You can tell this because unsubstantiated criticisms are multiplying. Matthew Parris, the Times columnist, has described him as "indefinably ghastly", the Daily Telegraph has accused him of "duplicity" and the Observer has demanded more "boldness".

But nobody has found a genuine skeleton in his closet, apart from a company BMW, which Nick Cohen exposed in the Observer. As Huhne's colleague for five years at the Independent on Sunday, and the person who edited his economics column for a period, I ought to be able to help.

Surely he must have written something foolish or inconsistent with his present political position, possibly under the influence of drink, drugs or a secret love affair? Alas, I can testify only that his copy was fluent, rigorous, sober and informative. This was a man firm in his opinions and not inclined to take any risks with them. I should add that he was an amiable and unusually helpful colleague, who would turn his filing cabinet upside down to find you, say, the dollar-yen exchange rate in 1957.

However, he had one significant vice: an uncontrollable passion for the Exchange Rate Mechanism or ERM (remember that?). On this subject, as IoS acting editor, I once wrote a dismissive leader, which Huhne considered tabloid in tone and mischievous in intent. He went to a higher authority in an attempt to get it suppressed. He failed.

I leave it to Lib Dem members to decide if this was conduct unbecoming of a future party leader. My advice is to go ahead and elect him, on the grounds that the shape of his face makes him seem to carry a permanent, reassuring smile.