Thomas Kinsella, of Orchid House, on James Street, Dublin, has gone on trial at the Central Criminal Court charged with murdering John Murdoch on August 27, 2011.
He has pleaded not guilty to murdering Mr Murdoch on Cushlawn Way/Cushlawn Dale in Tallaght.
Dominic McGinn, prosecuting, said that Mr Murdoch was stabbed shortly after midnight on August 26 last year.
He said the deceased was standing with two friends outside a shop in the Cushlawn estate when they became involved in a verbal altercation with another group.
He said it was the prosecution case that this other group comprised Kinsella, along with another man and a woman.
Mr McGinn said the altercation moved deeper into the estate and then turned violent.
He said it was the State's case that Kinsella was the only member of his group to be involved in the physical confrontation.
"Mr Kinsella pulled out a knife and stabbed John Murdoch in the chest," he said, adding that Kinsella then used the knife to threaten Mr Murdoch's two friends.
"He then stabbed John Murdoch another time."
He said the accused then ran off before the gardai arrived.
The jury heard the defendant's friends told gardai that the other men were the aggressors.
"That's likely to be the main issue of the case -- whether or not Mr Kinsella was acting in self-defence," said Mr McGinn.
Mr Murdoch was not breathing when he was rushed to Tallaght Hospital. He did not recover and was pronounced dead just before 1am.
The jury was told that a post-mortem found Mr Murdoch had actually suffered three stab wounds, the fatal wound penetrating his heart. The trial is expected to last six days.