The man living in the Kilkenny apartment was questioned by gardaí after being found with a knife in his hand and 21-year-old Kieran Monahan — one of two men taken from the scene with stab wounds — died later in hospital.
It has been confirmed by a number of sources that the DPP said no case should be brought against the man, aged in his 30s, arising from the incident.
It happened during a party on St Valentine’s night last year, four weeks after the 2011 Criminal Law (Defence and the Dwelling) Act was brought into effect by Justice Minister Alan Shatter.
It is understood the man who died and another man in his 20s had returned to the apartment following an earlier row there, and were trying to get back in.
While no reasons for the non-prosecution have been stated, it is understood the new legislation was a significant factor.
It provides that someone can use reasonable force to protect people in a home from assault, to protect property, or to prevent commission of a crime.
Under the law, anybody who uses force against a burglar, trespasser, or somebody trying to get into a home is not guilty of an offence if he or she honestly believes they were there to commit a criminal act.
A court or jury may not assess if such a belief was justified or not, only whether it was honestly held. However, in doing so, they may consider whether the accused had reasonable grounds for believing force was necessary.
In this case, sources say there is clear evidence that the person found with the knife had been seeking to prevent two men from entering the apartment.
He was on a 999 call to gardaí telling them two men were trying to force their way in, suggesting the DPP’s office may have felt there would have been too strong a defence under the 2011 act to warrant taking a case to court.
The fact no prosecution will be issued as a result of Mr Monahan’s death means the circumstances can be heard at an inquest, which is believed to be scheduled for June this year.