Neville and Doreen Lawrence have won the right to watch the programme today before it is aired at 10 o'clock tonight in a screening that will let the family's solicitor, Imran Khan assess whether there are any grounds to seek an injunction blocking the broadcast.
The programme's maker, Granada Television, says the interviews contain new evidence but Mr Khan last night said publicly screening new leads could be prejudicial to the ongoing police inquiry and could stymie future court proceedings.
Granada, which is making the current affairs show Tonight, featuring the interviews, is keeping the contents of the programme under wraps to try to minimise protests.
The broadcaster was still editing the interviews last night after spending the day in negotiations with Mr Khan. So sensitive is Granada about the programme that it produced a replacement documentary in case it had to pull the programme.
Mr Khan said: "We have not been told what the new lines of inquiry are but if there are new lines of inquiry they should be handed over to the police.
"The family have taken a very strong view as to whether this programme should have been made in the first place. Granada should not use evidence just to highlight or justify their programme."
The suspects from Eltham, south-east London - Gary Dobson, Luke Knight, David Norris and Neil and Jamie Acourt - were interviewed separately by Martin Bashir, the former BBC journalist who interviewed Diana, Princess of Wales for Panorama.
Jeff Anderson, the editor of Tonight, said yesterday: "The programme includes significant new material which may open new avenues of inquiry for the police. However, we are confident it will not prejudice any possible future prosecution of the five suspects.
"The programme is a rigorous and detailed interrogation of the five suspects and in no way provides them with a platform. No areas of questioning were off limits and no payment was asked for or made."
The Lawrences are upset because they believe they were told their views would be taken into consideration before a decision was made on whether to screen the programme.
The Metropolitan Police began legal proceedings under the Police and Criminal Evidence Act last week to try to gain access to the hours of video tape produced, but agreed to wait until the programme is screened before taking action.Reuse content