Vicky Pryce trial: have juries had their day in court? Its origins are lost in the mists of time. The ancient Athenians dreamt up the idea of defendants being tried by their peers - 500 dikastai, or fellow, male, free citizens. In Britain, it's thought that Viking invaders were the first to introduce 12 hereditary "law men." The Anglo-Saxon king Ethelred the Unready used the same magic figure of 12, for the number of minor nobles who investigated crimes. But the system of being judged by your peers was only fully bedded in after the Norman invasion. Henry III used juries of 12 free men to look into land disputes but, like the Anglo-Saxons, they actually investigated the legal cases, rather than dispassionately heard them like modern juries. By the time of Tony Hancock's beloved Magna Carta in 1215, the idea of the jury was integral to English law, as witnessed in the Latin words of Article 39, declaring that no free man should be convicted "nisi per legale judicium parium suorum" - unless through the legal judgment of his peers. For the past 800 years, that basic principle has worked pretty well. The only problem is, a good percentage of the population are now unable to understand certain concepts of criminal law, even if they understand English. A 2010 Ministry of Justice report revealed that two thirds of jurors don't fully comprehend the judges" legal directions when they retire to consider their verdicts. That problem was an acute one in the Vicky Pryce case, where her defence was particularly unusual - the ancient defence of marital coercion. Even though the judge, Mr Justice Sweeney, a 30-year veteran of the criminal courts, gave the jury extensive written and verbal directions about the definition of marital coercion, they still didn't get it. As the prosecuting counsel, Andrew Edis QC, said, this was a jury that didn't understand its function or the very basic concept of jury trial. Mr Justice Sweeney said he'd never seen such a situation in his career. The writer Peter Moffat, who spent nine years as a criminal defence barrister, was equally amazed by the collapse of Pryce's trial. Another will now be held. "Some of the questions the jury asked in the case are absolutely extraordinary," says Moffat, writer of the legal dramas Silk, Criminal Justice and North Square. They can't have been listening at all. It's hard to fathom. "Still, it's quite right that we don't know what goes on behind the doors of the jury room, to preserve the jurors" independence and integrity." Difficulties with juries have intensified over the past 10 years with the growth of the internet and social media, and the ability of a juror to investigate any defendant outside the courtroom, even if they're not as well-known as Vicky Pryce. Last year, Theodora Dallas, a former university lecturer, was jailed for six months for contempt of court, for carrying out online research on a criminal defendant while serving as a juror. The case was taken so seriously that the contempt proceedings were launched by the Attorney General, Dominic Grieve. In 2011, a juror was given an eight-month jail term for discussing a trial on Facebook with one acquitted defendant, and researching another online in a multi-million pound drug trial. "Social media is a massive problem and judges are incredibly worried about it," says Peter Moffat. The sentences are so harsh because the judges want the world to know that they'll come down hard on jurors using the internet. As lawyers, you understand the concept of categorising stuff, of keeping the case separate from the outside world; it's very difficult as a member of the public to close down parts of your brain. Inevitably you bring in outside influences. The other problem with juries is that, although they have the merit of being open to everyone, not everyone serves on them. The busy, the professional, the rich and the employed find it that much easier to claim an exemption. A booked holiday or a medical operation will bag you a deferral; a doctor's letter an exemption. In the Pryce case, most of the jury looked under 30. A skewed representation of the population will inevitably give skewed results. There have been concerns about the modern state of the jury trial in the higher echelons of our legal system, too. Yesterday, Lord Woolf, a former Lord Chief Justice, and Lord Macdonald, a former Director of Public Prosecutions, both backed jury trials but suggested they could be improved. Lord Macdonald defended the jurors" questions in the Pryce trial but argued that juries should be given more help. Their behind-closed-doors reasoning should be opened up, he said, so that judges could know how to direct them better. Lord Woolf even defended the jurors" question about the definition of reasonable doubt, saying that the guidance has changed over the years. He proposed that jurors might instead consider whether they were "sure" of a person's guilt. Neither peer, though, wanted to get rid of an ancient system that has worked well in this country since time immemorial. The law being its precise, perverse self, time immemorial was decreed as a legally recognised date - 1189, the beginning of Richard the Lionheart's reign - before being redefined as "Time whereof the memory of man runneth not to the contrary." The jury option still seems more fair than any alternative, however flawed it might be. "It's still absolutely the best system," says Peter Moffat. It may sound clichéd, but an adversarial, jury-based system is still a cornerstone of a democracy. If you let a judge decide - like in the Pistorius case - you're putting too much power in one person's hands. The judge in the Pryce case was clearly a very experienced barrister, a High Court judge with 30 years in criminal law. I'm sure he's utterly objective and independent, but I'd still prefer a jury. The majority of judges and barristers, and the majority of the British population, share that view. We still prefer to put our lives in the hands of 12 men and women, however angry or misguided they might be. Harry Mount is the author of 'My Brief Career - the Trials of a Young Lawyer" (Short Books)