Those who have yet to watch ITV's Judge Rinder may wonder why a show which is basically a reconstruction of the work of the small claims court has quickly generated one of the biggest daytime television audiences. The answer is almost certainly the judge himself. In his day-to-day life, Robert Rinder is not actually a judge but a fairly stellar criminal barrister whose practice focuses mainly on international fraud, money laundering and other forms of financial crime. But in his parallel existence on daytime TV, Rinder is the Simon Cowell of the bench, commenting in a cutting, witty and decidedly camp manner over civil disputes involving gardening, business loans and family members rowing over money in a British version of the hit American show, Judge Judy.

Litigants have agreed to have their cases ruled upon on TV rather than in a court of law and while the legal processes and rulings are consistent with the small claims court, Rinder does have a little more licence to be opinionated. He has already called one claimant "stupid" and told another that "if you had been at the Last Supper, you would have asked for ketchup". It is fair to say that his views are on the blunt side of forthright.

Yet Rinder says that until a few months ago, he had no aspirations to be on TV. "I used to write scripts and I attempted to sell one of them. I ended up talking to the head of ITV Daytime, Helen Warner," he explains. "She said she was not sure about the programme I suggested but asked if I had considered doing this kind of show."

Rinder thought it would be worth giving it a go. And the programme - now finishing its second week - attracts an audience of 1.1 million-plus, considerably more than the channel's breakfast show.

Although Judge Rinder is intended as entertainment, Rinder would not have accepted the brief if the show did not convey the correct values. "Of course there is an entertaining side to it but I wouldn't have gone anywhere near it if I didn't feel it had integrity. I have the genuine and authentic freedom to rule on cases that have legal implications in them as well as lessons we can all learn from."

Educated at Manchester University and with chambers in central London, Rinder may be new to TV but has also featured in Hello! magazine. His civil marriage to fellow barrister Seth Cummings was officiated by his friend, the actor Benedict Cumberbatch. He is not keen to talk about his private life and does not want his criminal practice to be affected by his TV work, although he does not think it will be. "Everybody at my chambers has been very supportive. If I had been at a chambers where people were less self-confident, it might have been more of an issue."

He adds that his TV persona, while perhaps not directly transferable to a criminal court setting, is not invented. "I speak to my clients in a very frank way," he says. "When you are confronting a case in which your liberty may be at stake, one has to be serious and deal with the law properly. But on the other hand, one needs to be relaxed and honest and sometimes to do that you have to be entertaining as well." He takes offence at accusations from tweeters that the programmes are scripted. "Absolutely nothing is scripted, although we can't show all the cases in their entirety because some of them go on for a considerable time."

I tell Rinder that from my viewing, his comments certainly come across as spontaneous. "I hope you are saying that in a generous way," he replies.

He adds that while he does not especially like the word, "performance", there is an element of drama in court. "Anyone who stands in front of a jury would be performing in some kind of way. However, I would say that people would run away from the show pretty fast if it were purely flim-flam. There has to be a sensible legal core, even if you appear to be silly or theatrical. Fundamentally people need to know that you understand the law and are applying it fairly and even-handedly."

It seems an odd question to be asking someone who is performing the duties of a judge but does he feel he is sometimes a little over-judgmental with those who stand before him? "I've encountered behaviour that could be described as moronic," he replies. "But we have all done stupid things. We've lent money to friends or bought something in circumstances we might not be sure about. And a lot of us have probably hired someone to do a job without getting a reference. I'm just pointing this out and hopefully it's helpful and instructive."

Although, on the surface, most of the disputes seem to be over money, Rinder makes the point that if you delve deeper, many of the cases on which he rules are about much more. "You ask any lawyer and you will discover that the bottom line in many cases, from the most basic to the most complex commercial disputes, comes down to personal feelings. These cases are inextricably bound up with people feeling hurt or betrayed in some way - they feel hard done by. Well, the lawyer's job is to say, 'I know you think you've been wronged but this is what the law says'. And that's the educational value of this process. It's certainly not a dull series of lectures but there are serious legal principles here."

Rinder - a regular JC reader - says that while his show has obvious similarities with that of Judith Sheindlin, aka Judge Judy, there are differences. "I think she is absolutely brilliant. I have watched one or two of her cases and she never gets it wrong. Our show is a bit longer and we allow the stories to come out more.

"We are equally funny," he adds, "but I would say she probably has a better command of Yiddish".

Judge Rinder is on ITV1 at 2pm on weekdays