The use of Twitter at a High Court bail hearing for Wikileaks editor Julian Assange was restricted by a senior judge on Thursday.
Justice Duncan Ouseley told journalists at the hearing that the use of Twitter during the trial would put them in contempt of court.
"There is to be no use of mobile phones, Blackberries or laptops, other than by [representatives]," said Justice Ouseley.
Mobile equipment can often record sound and images, which if used in a courtroom puts journalists in contempt, said the judge. In addition, the use of Twitter would be "a distraction to the atmosphere of the court".
Magistrate Howard Riddle allowed journalists to Tweet from a hearing in which Assange was granted bail on Tuesday, after a request from journalists. The hearing on Thursday was arranged after the Crown Prosecution Service appealed Riddle's decision.
Approximately halfway through the High Court hearing, Justice Ouseley stopped proceedings after being told by one of the court clerks that some journalists may have been recording sound.
"I would like to remind [everyone] that the use of any equipment to record is a contempt of court," said Justice Ouseley. "If steps have been taken [to record, the person responsible] can expect to go to prison today."
No sound or images at all can be recorded in a court, according to the Contempt of Court Act 1981. Even court artists, who record likenesses of defendants and salient personalities, cannot sketch those likenesses in court, but must memorise features and sketch or paint them afterwards. Line sketches of certain inanimate objects are sometime permitted.