Write an article for publication these days and the chances are that it will attract ill-informed comments. No longer content with sending in a letter to the editor and waiting to see if it is printed, readers now demand an instant right of reply on the publisher’s website.

And why do so many readers post vituperative responses that they would not dream of making to a writer in person? It must surely be because most such comments appear anonymously.

Commentators find this disconcerting. We want to know whether the person who has accused us of writing nonsense is someone whose opinions we should take seriously. We may even wish to seek redress against such readers. But first we need the publisher to tell us who they are.

That was the position that Jane Clift found herself in. Her story goes back to 2005, when she came across a small boy deliberately damaging plants at a public park in Slough. When she tried to intervene, Clift was threatened by the boy’s family. Eventually, she was advised to complain to Slough Borough Council.

So infuriated was she by Slough’s response that she found herself placed, unjustifiably, on the council’s semi-public ‘register of violent persons’. Clift sued the council for libel and was fully vindicated: a jury awarded her damages of £12,000 in 2009 and the council lost its appeal at the end of last year.

Not surprisingly, Clift’s victory was reported in the Daily Mail and on its website. Around 40 of the newspaper’s readers posted comments, almost all of them welcoming the outcome. But two were critical.

Having noticed the two comments some months later, Clift wanted to sue the authors for libel. First, though, she needed an order requiring the newspaper to disclose their names. A Norwich Pharmacal order, as it’s called, may be granted against a defendant who is ‘mixed up in the wrongdoing so as to have facilitated it’.

Last month, Clift’s application to the High Court was dismissed by Mrs Justice Sharp. Exercising her discretion, the judge said it was difficult to see how any readers of the newspaper’s website would take the two readers’ comments seriously.

Sharp’s full judgment is not readily available. But the Mail was represented by Sarah Palin of One Brick Court and a summary on her chambers’ website reports the judge as finding it ‘fanciful that any reasonable and sensible reader could construe these postings to be anything other than pub talk’. Sharp ruled that the two comments should not be read in isolation from the article itself, which had supported Clift.

And, said the judge, any libel claims were ‘highly likely to fail, not least because a defence of honest comment would probably succeed in both instances’. Identifying the two individuals would also be disproportionate, given their expectation of privacy.

The ruling can be seen as good news for websites that publish comments which are relatively transient, are not intended to be taken seriously and are unlikely to cause any real harm. But newspapers have not been given a get-out-of-jail-free card which they can use whenever they publish something online by mistake.

That much was clear from a High Court case that the Mail lost last week. It followed the trial and conviction in Sheffield of Ryan Ward, 19, for murdering an older man who had tried to stop a fight.

On the opening day of the trial, the Mail website published a picture of Ward holding a pistol with his finger on the trigger. The picture appeared shortly after 5pm and remained online for nearly five hours, even though the journalist who supplied it had warned the picture desk that the gun should not be shown in any published image.

The attorney general, Dominic Grieve, took contempt of court proceedings against the Mail – and the Sun, which had published a photograph of Ward that was partly cropped but had been online for longer. Grieve argued that the photographs had created a substantial risk that the course of justice would be seriously prejudiced against Ward.

Lord Justice Moses and Mr Justice Owen found that the trial judge had ordered jurors not to ‘consult the internet’. But the jury had not been told to avoid reading contemporaneous online accounts of the trial. So any juror who saw the offending photograph would not have been disobeying the judge’s order.

In the event, no juror was found to have seen the photograph. But that made no difference. If a juror had seen it, the jury would have been discharged. That amounted to serious prejudice. The newspapers’ publishers were found guilty of contempt last week and will be sentenced later.

They have some reason to feel hard done by. The Mail and Sun argued that, even if the jurors had seen the offending photograph, they would still have decided the case on the evidence.

That must be right. Moses and Owen referred to research by Professor Cheryl Thomas suggesting that a quarter of jurors in high-profile cases had seen information about their case online while the trial was continuing. And yet it suits judges to trust jurors and believe them when they say they have not searched for, or found, anything inappropriate.

Of course, websites should not publish defamatory or prejudicial material. Moses and Owen were right to say that ‘instant news requires instant and effective protection for the integrity of a criminal trial’. But we must be honest with ourselves and recognise that, in the internet age, juries are bound to know more than they hear in court.