Less than two years ago it is possible such images would never have been seen by the public. Even at the trial's end, the images might not have been released by the prosecuting authorities - the CPS and the police - to the media. Today images shown in court may be seen in the news media during the trial. The importance of this change for court reporting cannot be over-emphasised.

So what brought about this sea-change? The answer lies in a protocol drawn up by the Crown Prosecution Service (CPS) that commenced in October 2005. The protocol arose from meetings between the CPS, ACPO (Association of Chief Police Officers) and press and TV representatives. The media's point was, if the public can see film footage used in court whilst sitting in the public gallery, why shouldn't they see the same footage in news reports?

The new arrangement are designed "to provide an open and accountable prosecution process" by significantly increasing what is disclosed by the prosecution to the media.

Certain material will normally be released to the media - police videos of the scene of crime or property seized, transcripts of interviews read out in court, videos or photographs showing reconstructions of the crime and CCTV footage of the defendant. Other evidence - such as CCTV footage or photographs showing the defendant and victim, or the victim alone - may only be released after consultation with victims and witnesses.

This protocol has brought about probably the biggest change in court reporting in the past 20 years. The 21/7 trial was the best example yet of how it works because so much of the evidence was captured on CCTV cameras.

Some images were released at the early stages of the investigation when the police were searching for the suspects. Other material - CCTV footage, photographs and police film footage - was released to the media only after being shown to the jury in open court. So the public saw, for example, images of Yassin Omar fleeing in a burka, the prosecution's own footage of the reconstruction of the bomb and footage of the moment Ramzi Mohammed tried to detonate his bomb on the tube.

ITV News had broadcast exclusive footage of the initial arrests filmed by a member of the public. At trial, different footage taken by police of the same incident was made available to all broadcasters.

The protocol has brought open justice to a new level. The CPS and the DPP, Sir Ken Macdonald QC, deserve credit for their innovative policy. It is a good example of what can be achieved if a public authority is prepared to trust the media a little. By engaging with the media, the CPS's initiative has resulted in many benefits. The public are better informed. They can see evidence presented in court, without travelling to court. The hearing itself also has greater transparency.

The same measure of trust could be applied to a range of open justice issues, particularly televising the courts. The 21/7 trial is a classic case where televising the sentencing by Mr Justice Fulford would have had a real public benefit, showing justice being done.

The Ministry of Justice has not yet announced its decision on the 2005 Public Consultation on Broadcasting Courts. In England and Wales a 1925 statute prevents broadcasting proceedings, so without travelling to court the public could not see the 21/7 trial.

The protocol has been a success. There are clearly sensitivities involved, not least issues of contempt of court and the rights of the victims and the defendant's right to a fair trial. But this protocol has not resulted in trials being disrupted. The sky has not fallen down. The real beneficiary is the public, now better informed. That is a major step forward.

The writer is the head of compliance at ITN and helped to set up the protocol. www.cps.gov.uk/publications/agencies/mediaprotocol.html