“Every court in the land is open to every subject of the King” declared the Earl of Halsbury in the famous case that enshrined the open justice principle in British law. Another law lord endorsed Jeremy Bentham’s conclusion that “Publicity is the very soul of justice – it keeps the judge, while trying, under trial.” That case was back in 1913, but its logic has never been applied to make public scrutiny of justice a reality, by permitting television coverage of trials. Now that the government’s victims’ commissioner, Helen Newlove, has declared that televising courts could improve the system, and ITV is about to show a documentary featuring footage of proceedings in the court of appeal, it is time to reconsider the ban on filming trials.

Court proceedings are sometimes highly significant public occasions, and understanding of them needs much more than a few breathless comments by a reporter pictured outside the court door, with frequently inaccurate “illustrations” – in reality, cartoons by “courtroom artists” banned from sketching inside the courtroom. Press reports are always incomplete and fail to capture the drama, or the oral emphasis and body language that can be crucial in a criminal trial.

Consequently, there is a vast public misunderstanding of the criminal process and lack of appreciation of the role of judges and lawyers – one reason why this government has got away with slashing legal aid and the budget of the Department of Justice. There is a legitimate public interest in important trials – recognised often by tribunals, such as Grenfell, which can permit their proceedings to be televised.

Of course, the televising of trials would have stringent protocols: the faces of the jury should never be shown (the verdict would be a voiceover) and defendants would not be pictured from the dock unless they protested from it or went into the witness box to give evidence. Barristers and expert witnesses could not avoid scrutiny, but the judge would have wide discretion to bar coverage of vulnerable witnesses or those who had a reasonable objection, and the power to disallow filming (except of him or herself) if it could prejudice the defendant.

There would be obvious advantages in appealing wrongful convictions: appellate courts would not dodge the issue by deferring to the trial judge “who unlike us has seen the witnesses”, when they could evaluate testimony themselves by hearing and seeing it played back. Barristers frequently wish they could include as a ground of appeal an objection to a trial judge’s prejudicial tone of voice or body language – prejudice which is not apparent from reading a trial transcript.

The Bar Council some years ago recommended the televising of trials, but impetus was lost after the distaste at watching the OJ Simpson proceedings, perceived here as a media circus. But when the Wall Street Journal commissioned a follow-up study of the impact of the television coverage in the US, it found that it resulted in an amazing drop in the number of people seeking exemption from jury service: citizens wished, much more than before, to play their part. Moreover, it caused those who did serve on juries to pay less attention to lawyers and their arguments, and to concentrate on the evidence.

There are other public benefits. Had the trial of Tommy Robinson been seen on television, the conspiracy theory that he was punished for exercising a right to free speech could hardly have taken hold worldwide (and the procedural unfairness would have been more clearly and quickly appreciated). Historic cases, had they been videotaped, would genuinely fascinate: imagine if we could watch the real trial of Jeremy Thorpe, or of Clive Ponting, or the “Iraqgate” case in which the Thatcher government kept evidence of innocence from the trial of men accused of sending bomb-making equipment to Saddam Hussein (until trade minister Alan Clark admitted to lying – or at least being “economical with the actualité”). It would be informative, too, as well as entertaining, to be able to watch a few George Carman cross-examinations of gold-diggers seeking libel damages for reputations they did not deserve.

There will always be claims of privacy, but trials are public occasions. Those convicted of serious crimes, certainly, might be thought to have forfeited any privacy rights in respect of the proceedings which led to their conviction, and could have no objection to a programme that reconstructed the case using courtroom footage. My own experience in proceedings in other countries has been that televising trials means that the barristers are better prepared, the judges better behaved, and the public better informed.

• Geoffrey Robertson QC is head of Doughty Street Chambers. His autobiography, Rather His Own Man, is published by Biteback