The judge in the Graham Dwyer trial has warned people attending the proceedings not to tweet anything said in the absence of the jury.
Mr Justice Tony Hunt gave the warning today, telling members of the public that there were restrictions on reporting matters discussed while a jury was not present.
He explained that such discussions could not be reported until a trial was over and for a good reason.
His comments followed the tweeting of material by a member of the public on Tuesday afternoon.
The judge said he accepted that the person had been unfamiliar with the rules, but warned that "someone was going to spend some time in jail for contempt" the next time it happened.
Although the jury was not in court when he gave this warning, he asked that it be reported. Both the prosecution and defence consented.
Mr Dwyer (aged 42) is on trial at the Central Criminal Court, charged with murdering Dubliner Elaine O’Hara at Killakee, Rathfarnham, Dublin on August 22, 2012.
The Cork-born father-of-three of Kerrymount Close, Foxrock in Dublin has pleaded not guilty to murdering the 36-year-old childcare worker on that date.
The trial has heard that Ms O’Hara was last seen in Shanganagh, South Dublin that evening, hours after she was discharged from a mental health hospital.
A cause of death could not be determined when her skeletal remains were discovered at Killakee on September 13 the following year.
It is the State’s case that Mr Dwyer stabbed her for his own sexual gratification.
The trial continues before the jury of five women and seven men.