During the trial in Sydney, Australia, of two men accused of manufacturing narcotics, the jury seemed unusually diligent in taking copious notes. But after more than 60 days of hearings, District Court Judge Peter Zahra aborted the trial last month when the jury forewoman confessed that, in fact, she and four other jurors had been playing Su Doku in court for much of the proceedings. “It helps me to keep my mind busy,” she explained, as “some of the evidence is rather drawn out” and “it doesn’t distract me too much from proceedings”.

The jury misconduct had been noticed by one of the defendants while giving evidence. None of the 20 police officers who had been in the witness box had observed any wrongdoing. In his 1956 Hamlyn lectures, Lord Devlin suggested that trial by jury is “the lamp that shows that freedom lives”. Unfortunately, as the Sydney case confirms, the lamp sometimes goes out.

There are many precedents for jurors failing to pay attention to proceedings. In 1989 a kidnapping trial at the Old Bailey was halted after a juror told the judge that he could not listen to any more evidence as it “was not my scene”. In 2000 a woman juror was fined £100 for contempt of court after she missed the second day of a murder trial at the Old Bailey because she had been awake all night after a row with her husband. Judge Warwick McKinnon fined a juror £500 at Chelmsford Crown Court in 2000 for refusing to attend the judge’s summing-up in protest at the refusal of the Court Service to pay the cost of his chauffeur driving him to and from the court. In 1993 Taunton Crown Court discharged a juror who came to court in a medieval jousting costume and said he had not had time to change.

Jurors may misunderstand their function. In 1997 Judge Wilkie, QC, ordered a retrial at Luton Crown Court after a juror told the defendant: “Why don’t you plead guilty? You are f***ing guilty.” The juror told the judge that he had spoken out because “it was an insult to my intelligence for him to plead not guilty”. In 1995 a trial at Northampton Crown Court was abandoned after a woman juror told the usher that she was so angry at the rudeness of the defence barrister to a prosecution witness that “I want to hit him. He is contemptible. I don’t know how I can remain impartial.”

Misbehaviour by jurors may take many forms. In 1986 Judge Jean Graham Hall dismissed a juror from a case at Croydon Crown Court after he left a note about her for defence counsel: “How would you like that as a mother-in-law?” A woman juror was fined £100 by Judge Christopher Compston at Reading Crown Court in 2003 for reading a magazine and filing her nails during a case. A. P. Herbert, in one of his misleading cases, was only just on the fictional side of the line in suggesting that “a member of the jury may powder her nose in the box, but not use lipstick or eat oranges”.

Some jurors are just impossible. In 1991 Judge Rucker dismissed a male juror at the Old Bailey who constantly interrupted proceedings to ask for evidence to be explained and to argue legal points from the jury box. When the judge told him a point he raised was irrelevant, the juror replied: “Well, I think it is relevant.” The other jury members complained about the conduct of the man they called “Mr Busybody”. At the Old Bailey in 1993 Judge Gerber discharged the jury after six members complained that a seventh had been “a pain in the **** from the start. A self-opinionated, bullying know-all. We can’t carry on with him among us.” In 1993 Judge Hawkins, QC, discharged a jury at the Old Bailey when two bickering jurors nearly came to blows after one accused the other of burgling his flat. In 1994 a judge at Exeter Crown Court discharged a jury because two jurors complained that another had fleas. In 1995 a murder trial at Winchester Crown Court was halted after the jury complained that they could not concentrate because defence lawyers kept watching them.

In 1994 a jury trying a murder case at Hove Crown Court retired overnight to a hotel while they considered their verdict and used a Ouija board to try to make contact with the deceased. In 1998 Judge Esmond Faulks removed a male juror from a case at Newcastle upon Tyne Crown Court after he asked about the defendant’s date of birth so he could identify his star sign in order to assess the likelihood that he had committed the offence. In 2003 a female juror was discharged from an Old Bailey trial because she refused to look at the documentary evidence as she was reading a book on witchcraft and meditating.

So the Sydney Su Doku jury were not the first to focus on irrelevant distractions. Another jury will now concentrate on deciding whether the defendants, rather than a puzzle, are superfiendish.

The author is a practising barrister at Blackstone Chambers in the Temple and a Fellow of All Souls College, Oxford

Times Recommends

• Clifford Chance sets out to improve its public image
• Bennett starts 16-year sentence for Refco fraud
• FSA challenged over insider trading case