Supreme Court says lethal weapons ‘unjustifiable’ in emotional situations

David Mahon loses Supreme Court appeal against severity of manslaughter sentence

A Dublin man has lost his Supreme Court appeal against the severity of a seven-year sentence for the manslaughter of his partner's son who died from a stab wound.

In the court’s unanimous judgment rejecting David Mahon’s appeal, Mr Justice Peter Charleton said the introduction of a lethal instrument into an “emotional situation” is “unjustifiable”.

“Absent an attack with deadly force and an action in self-defence in extreme circumstances, there can never be an excuse for the production of a knife.”

Having analysed sentencing patterns in various manslaughter cases, he also stressed attacks by men on women “should be regarded with particular seriousness”.


His judgment has set out guidelines for sentencing judges in manslaughter cases where two paths to the same jury verdict may be possible.

David Mahon (48) had denied the murder of Dean Fitzpatrick (23), the older brother of missing teenager Amy, in May 2013.

Mr Fitzpatrick received a stab wound to the abdomen outside the apartment shared by his mother, Audrey Fitzpatrick, with Mahon at Burnell Square, Northern Cross, on the Malahide Road in Dublin.


The young man was taken to hospital after he was found semi-conscious on a pavement near the apartment by passers-by about 11.10pm on May 26th, 2013. He was pronounced dead less than two hours later.

Mahon had been in a relationship with Audrey Fitzpatrick for 12 years by the time her son died.

The prosecution case was that Mahon was drunk, angry and agitated when he thrust a knife into his stepson with deadly intent. Mahon claimed his death was an accident or possible suicide and Mr Fitzpatrick had “walked into the knife” while they had been arguing.

A Central Criminal Court jury found Mahon guilty of manslaughter and he was sentenced to seven years in jail by Ms Justice Margaret Heneghan in June 2016. After the Court of Appeal upheld the sentence, he secured a further appeal to the Supreme Court.

Giving that court’s judgment on Thursday, Mr Justice Charleton welcomed “valuable” research of the Judicial Researchers Office showing manslaughter sentences range from life or very long determinate sentences to, in very exceptional circumstance, a non-custodial option. Other research showed an increase between 2001 and 2016 in the time served, on average, by those sentenced to life imprisonment.

In this case, he said Mahon apparently believed Dean Fitzpatrick took a water bottle from his bike some days before the stabbing incident and had sought to contact him.

He said, after Mr Fitzpatrick called over to Mahon’s flat, Mahon came after Mr Fitzpatrick with a knife and the jury found he did not intend to kill or cause serious injury.

Aggravating factor

Mahon’s introduction of a knife and his admitting brandishing of it was an aggravating factor and, after the death, he made no effort to secure help for a man seriously injured by him and fled the scene, the judge said.

Because the sentencing judge had not provided an analysis of the facts which she had accepted as beyond reasonable doubt following the verdict, the Supreme Court on appeal could not state what facts were open to her to find as to the narrative leading to the victim’s death as that was a matter for the trial judge, he said.

This case may thus be regarded as an “exception” from what ought to occur, which is that a sentencing judge should provide a clear narrative as to the facts accepted.

The best analysis possible on the basis of what the trial judge had said was of culpability based on the introduction of a weapon and what the trial judge called a “spontaneous” type action.

Because the Supreme Court had no sentencing narrative, and had not sat through the trial, it cannot take a different view of the sentencing facts than the trial judge, he said.

On her analysis, it appeared a “lenient” view was taken amounting to production of a knife a part of a “psychic assault” and either an unfortunate spontaneous action or collision.

That view of culpability placed the matter in the medium culpability end of the spectrum of manslaughter offences, with sentences between four and 10 years.

On that basis, and without commenting whether a more serious view could have been taken as that was a matter for the sentencing judge, the court would not alter the sentence, he ruled.

Mary Carolan

Mary Carolan

Mary Carolan is the Legal Affairs Correspondent of the Irish Times