Brian Rattigan has won his appeal against his conviction for the murder of a man in Dublin 16 years ago.
Rattigan was sentenced to life in prison in 2009 after a jury convicted him of the murder of 21-year-old Declan Gavin outside a fast food restaurant in Crumlin Shopping Centre in August 2001.
He is also serving a 17-year sentence for drug dealing from Portlaoise prison.
The Supreme Court found that comments made by the trial judge to the jury at the end of the trial "went further than were desirable".
Giving the majority judgment in the case, Ms Justice Iseult O'Malley said there was a real possibility that the comments made by the trial judge may have been seen as reflecting his personal opinions and that they may well have influenced the members of the jury in their view of the defence case.
The court will sit again after Christmas to hear the views of the Director of Public Prosecutions on whether or not a retrial should be ordered.
Orla O'Donnell: Supreme Court proceedings being recorded again
The 36-year-old was convicted of murder in December 2009.
The jury found that he intentionally stabbed Mr Gavin to death outside Abrakebabra in the early hours of 25 August 2001.
The jurors’ majority verdict of ten to one came after deliberations lasting more than 11 hours over three days.
It was the final comments of the trial judge Mr Justice George Birmingham to those jurors that have now led to the quashing of Rattigan’s conviction.
At the end of a criminal trial, the jurors listen to closing speeches from the prosecution and the defence.
Finally, the judge addresses them in what is known as the judge's charge.
The judge usually summarises the evidence and closing speeches and explains legal principles to the jury.
Rattigan’s senior defence counsel Brendan Grehan said he would have described the remarks made by Mr Justice Birmingham to the jury in this case as a "model of fairness and balance", until the last five minutes.
In his final remarks, Mr Justice Birmingham said that if the prosecution was wrong about Mr Rattigan being the "knife man", then Mr Rattigan had been "most unfortunate".
He went on to summarise the coincidences in the case, saying eight times that Mr Rattigan appeared to have been "unlucky".
He ended by telling the jurors that before they could convict "they had to be satisfied that the suggestion of coincidence amounts to an affront or an insult to your intelligence".
Rattigan’s lawyers immediately asked for the jury to be discharged.
The judge refused, saying he was entitled to comment and had set out the respective contentions of the parties.
The jury went ahead with their deliberations and Rattigan was convicted.
The Court of Appeal found the trial judge had not mischaracterised the defence and that the judge made certain observations on the logic of the evidence "with which it was difficult to argue".
The Appeal Court did agree to certify a question to the Supreme Court relating to the admissibility of statements of evidence.
Rattigan’s lawyers went to the Supreme Court and also got permission to challenge the judge’s summing up.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
In her ruling, with which Chief Justice Frank Clarke and Mr Justice Liam McKechnie also agreed, Ms Justice O’Malley found that, unintentionally, the trial judge engaged in what could be seen as advocacy in favour of the prosecution.
She said his comments undermined the defence case by reference to an argument not made by the defence, and by subjecting that argument to "sustained sarcasm".
She said the comments could not be seen as anything other than an invitation to the jury to reject the defence case out of hand.
Ms Justice O’Malley said the comments came at the end of a "model" charge to the jury.
The judge, she said, then launched into a "devastating critique" of the defence case without any reference to any weakness there may have been on the prosecution side.
Ms Justice O’Malley said that because of the vital part played by juries in the criminal justice system, it was essential that the judge, should respect the independence of the jury’s role.
She said he or she should not influence the jury’s verdict by communicating or seeming to communicate personal views, that appear to point to a particular verdict.
The judge found the comments in this case went further than desirable.
There was a real possibility that they may have been seen as reflecting his personal opinions and may have influenced the members of the jury in their view of the defence case.
Ms Justice Elizabeth Dunne gave a dissenting judgment and Mr Justice Peter Charleton agreed with her.
In her ruling, Ms Justice Dunne said the dividing line between permissible and impermissible comment in the course of a charge is a narrow one.
But in her view Mr Justice Birmingham’s comments in this case "remained within the dividing line of permissible comment".
The court allowed Rattigan’s appeal by a majority of three to two.
Rattigan is also serving a 17 year sentence for drug dealing from prison.
He is appealing that conviction and a date for that appeal may be set next week.
This matter will be back before the Supreme Court early next year when lawyers for the DPP will tell the court whether or not they want a retrial to be ordered.
