I first saw Sidney Lumet's film, on which this stage play is based, years ago, and loved it. Watching the play now, it's remarkable how true it remains to my experience as a juror.

I did two weeks' jury service earlier this year, sitting on two cases – one involved the possession of a weapon, and the other grievous bodily harm. Neither was quite as exciting as the murder case in the drama, but there were certain parallels: the weapon in the first trial was a knife, as in the play; and the defendant was also a young black man.

Nobody shouted or got into a fight in our jury room – but I definitely recognised the tense atmosphere. Our foreman was always trying to keep order, and in one of the cases, the majority of jurors initially favoured a guilty verdict, and gradually changed their minds. That process was very similar to the one depicted here: a case of people slowly persuading the other jurors of their position. As in the play, we did all talk about the defendant's backgrounds, too: for instance, whether coming from a tough area made someone more likely to have carried a knife for defence.

Today, in contrast, our jury had a roughly even balance of men, women and ethnicities. There's something very uncomfortable about seeing an all-white male jury in the play, especially when one juror starts giving racist views. Nobody in our jury said anything like that, and I don't think anyone would have tolerated it if they had.

We couldn't nip off to the toilet to discuss the case, as they do on stage – there was just one loo, and you were expected to go in alone. But the whole deliberation process is still taken very seriously: we were shut in a room deep in the building, behind two sets of locked doors, and our mobile phones were taken away. That's as it should be. Here in the UK, thank God, we don't send anyone to the electric chair, but serving on a jury is a big responsibility: send a young person to prison, and you change his or her life for ever.

• Emma Danvers is a pseudonym.