When you have a complex and demanding task to be done, you'd be asking for trouble if you just went out and hauled in the first person you met on the street to do it. But that's pretty much how things work in our justice system, where randomly selected people are required to listen, to understand, interpret, weigh up and finally evaluate days' or possibly weeks' worth of detailed evidence and decide whether other people accused of committing offences actually did so.

If you are like me, you probably grew up without ever much questioning the idea of "12 good men and true" nobly upholding the glory of democratic justice. And you have probably not had much reason to do so, if you have not yet found yourself in a room with 11 other "good" men and women. But take it from me, once you are in that room, you are likely to ask yourself if you would want these people sitting in judgment on you, should you be unfortunate enough to be in the dock. And you are likely to decide that you wouldn't.

Illustration: Jim Pavlidis.

Don't get me wrong. Being on a jury has the power to make you just as much aware of your own limitations as those of others. One bleak morning, I sat in a courtroom – all panelled wood and black-gowned barristers – and listened as a list of rape and sexual assault charges was read out. To each of them, the accused man responded, "Not guilty." Sitting in the jury box, I tried to stop myself trembling and steeled myself to look at the kind of man who would do such things.

It took a comment from the judge to shock me back to reality. Remember those old words, “innocent until proven guilty”? The man said he was not guilty and the law concurred with him. He had been charged, not convicted, and it was up to us, the jury, to decide if he had done the crime. That's why we were here.