The family of a man jailed for taking a photograph on his BlackBerry inside court have criticised the "pointless rules" which govern courtrooms.

Paul Thompson, 19, is serving a two-month sentence in HMP Bedford for contempt of court. He was in the public gallery of Luton Crown Court on Friday afternoon when he was asked to leave for being disruptive. It was later discovered he had taken a photograph of the court on his mobile phone and he was arrested.

Thompson appeared before Judge Barbara Mensah an hour later and was handed a custodial sentence. As she passed sentence, Thompson said: "That's stupid, man." His family have had no contact with him since then.

His brother Lee, 21, told The Independent: "If they have cameras in Parliament, why not in court? Anyone can go in off the street and watch so it's just the Government making up pointless rules – it's 2011, not the 1800s.

"It's a stupid thing to do. But you'd think he'd just get a bollocking. I didn't think you'd go to jail for it. I didn't even know they could grab someone in court and take them straight to jail. The court wasn't even in session. As far as I knew it could only be an offence if it affected the case."

John Livingstone, a barrister who was hurriedly appointed to represent Thompson, said: "He seems to have been texting a girl at the time and decided to take a photograph to prove where he was. The officer in the case being sentenced followed him out of court, asked to see his phone and – to be fair to Mr Thompson – he unlocked his phone and showed the officer the photograph he had taken. The judge felt it was the sort of contempt that she should send out a message about."

The sudden nature of the case meant Thompson was sent to prison without any money or possessions. His main concern was a young puppy locked inside his house – after he was sentenced friends had to break down his front door to rescue it.

Frances Crook, chief executive of the Howard League for Penal Reform, said: "Young people are so used to using their phones like this these days, and a little understanding of that by the court would not have resulted in a prison sentence. There is a degree to which it appears the justice system is not keeping pace with technology."

She added: "Short spells in custody have been shown to be very ineffectual and they are a costly way of dealing with the issue."