The use of smartphones and social media pose a risk to jury trials that cannot be completely overcome, a Court of Appeal judge warned.

Giving a lecture at the Criminal Bar Association’s annual conference, Lord Justice Singh stressed that juries are a ‘fundamental feature’ of our system for trying serious criminal cases, and ‘juries take their task very seriously and value the responsibility and trust which are vested in them’.

But, he said, with the use of IT by members of the public in a jury trial ‘occasionally something can go wrong’.

‘These days a smartphone can do so many things that were undreamt of even a few years ago; and can do so almost instantaneously,’ he said. Singh LJ recalled an incident during a murder he had tried at Lewes in 2013 when his ruling rejecting a submission of no case to answer against one of two defendants had been circulated on social media by someone in the public gallery.

‘Thankfully it was possible to have this material removed quite quickly and no one suggested that any member of the jury had seen it,’ he said.

Singh LJ said: ‘One cannot emphasise enough the warning that the judge now gives to jurors at the start of a trial not to research the case on the internet, including the possibility of a contempt of court and penal sanctions being imposed.

‘But one cannot guarantee that there will never be problems when the use of smartphones is so quick and easy.’