The challenge has not been taken up. So far.

But as solicitors for two of the five last night said they were considering suing for libel, the newspaper's tabloid rivals were admiring. And, in a highly unusual intervention, Home Secretary Michael Howard said the Mail had not necessarily broken the law by naming the men.

The five, all from south-east London, provoked widespread outrage earlier this week when they refused to answer questions at an inquest into the death of Stephen Lawrence , an 18-year-old student stabbed while waiting at a bus stop in Eltham, south-east London, in April 1993. Questioned by the barrister acting for the dead youth's family, they all claimed the common right of 'privilege' against self-incrimination.

The jury returned a unanimous verdict of unlawful killing, adding that Mr Lawrence had been killed in an unprovoked racist attack. Under English law they were not allowed to name those responsible.

Despite the threat of legal action, the Daily Mail was unrepentant last night. 'This is not a kangaroo court, because we're not trying them. What we are doing is challenging them to put up a defence, because this is something they have refused to do so far,' said the paper's deputy editor, Peter Wright.

Mr Wright said the paper had taken its stand because of the seriousness of the case and the issues it raised - though in the past it has covered the story less comprehensively than most national newspapers, with 20 stories on the case in almost four years, compared with 39 in the Guardian. Paul Dacre, its editor, also knew Neville Lawrence, Stephen's father, it was reported last night. Mr Lawrence had done some work at Mr Dacre's home, the Times said.

Today, the paper goes further. It devotes two pages to a covertly filmed police tape. Still photographs show one of the accused men brandishing a knife, demonstrating to others how best to stab.

The footage, filmed from a tiny camera hidden in a plug pocket, shows three of the men it accused of murder locked in racist conversation. It will be screened on Channel 4 tonight.

Tabloid editors praised the Mail last night. 'A courageous piece of journalism,' said Stuart Higgins, editor of the Sun. 'It is newspapers' job to change laws and regulations when they believe they are wrong.'

Piers Morgan, editor of the Daily Mirror, was equally complimentary. 'They (the Mail) were saying exactly what the whole country was thinking. It was a brilliant piece of journalism and I wish I'd thought of it.'

Elsewhere, support for the Mail's action was more qualified. Channel 4 newscaster Jon Snow said: 'I'm glad that they've done it, but I feel queasy about it too. I'm glad because the law failed, but I'm queasy because I believe in the rule of law.'

SNOW'S quandary was shared by several liberal commentators, who believe trial by media is wrong but are sympathetic to the Mail's verdict. On the one hand, they were eager to see the Lawrences get a just outcome in the case of their son. On the other, they acknowledged that to support the Mail's stand is to forgo any secure tenancy on the moral high ground when it comes to criticising the media for putting itself above or outside the law.

Rosie Boycott, editor of the Independent on Sunday, said: 'It's not one of the greatest precedents, but in this case I think it was good. I think it shows how much the media and ordinary people have become people with the right to swing the course of justice.'

However, to concede that there are times when raw populism, as characterised in the Mail's front page, can be more just than the judicial system itself could one day blow up in their faces, claimed media commentator Stephen Glover.

'People should not judge this by whether they think the people were guilty or not. This is the usurpation of the role of the judiciary by a newspaper, and that is wrong.

'Unless Paul Dacre was present at that bus stop and saw that those five men were equally guilty of murder, then he shouldn't have done it. They cannot be sure that they did it. They should investigate whether there had been a miscarriage of justice and shown how,' he said. Hugh Stephenson, Professor of Journalism at City University, was equally critical: 'You shouldn't make serious accusations against people unless you have proof. Courts are for finding people guilty, not newspapers,' he said.

But while the debate about whether the end justifies the means raged in newsrooms, many expressed astonishment that such a row should be provoked by the Mail at all, given its record of reporting racial incidents in the past.

Will Hutton, the editor of the Observer, believes that the Mail's front page sets a dangerous precedent. 'But my first thought,' he said, 'is that it is so remarkable that the Daily Mail should so publicly come out in support of a miscarriage of justice which involves a black British citizen.'