The nature of manslaughter: Manslaughter is the unlawful killing of a person, falling short of murder. A charge of murder will be brought where the DPP considers that the suspect intended to cause the death of or serious injury to the victim.
There are two routes to a manslaughter conviction. One that was not relevant in this case is where a person acts with gross negligence or recklessness, leading to the death of another person or people.
An extreme example would be where a person who had consumed a large amount of alcohol got into a car and drove it the wrong way down a pedestrianised street filled with shoppers.
When considering a prosecution for murder or manslaughter, therefore, the DPP must examine whether the death resulted from an intention to cause death or serious injury.
If this is the case, he will charge the person with murder.
If it is not, but the death resulted from the actions of another person where it was intended to cause harm, the charge of manslaughter will be considered.
The accused person does not have to intend to cause serious harm to be guilty of manslaughter.
The intention to harm will do. He or she must be involved in an act that is both unlawful and dangerous.
A case that went to the Court of Criminal Appeal in 1966 illustrates this point in the Irish law on manslaughter. The appeal was against a conviction of manslaughter against two dockworkers, who had been involved in a fight where a man was stabbed and later died.
It was claimed in the appeal that the man who stabbed him had not thought that carrying the knife that caused his death was a dangerous act.
The two dockworkers had carried a knife and a spanner to where work was being handed out at Dublin docks, intending to assault a man who had been offensive to the men's sisters who were working in a nearby café.
A fight developed involving at least eight men. One man, not the intended victim of the planned assault, was stabbed during the fight and later died. The men wielding the knife and the spanner were convicted of manslaughter.
The Court of Criminal Appeal upheld the guilty verdict, stating that the act leading to the death must be unlawful and dangerous.
Whether or not it was dangerous was a matter of fact for the jury; what the defendant himself thought on the matter was irrelevant.
The jury in the Brian Murphy trial had to decide whether the acts committed by the three youths they convicted of violent disorder - and therefore of an unlawful act - caused the death of the victim. Observers at the trial agreed this was a very difficult decision.
In a manslaughter trial, as in any criminal trial, the jury must also decide its verdict "beyond all reasonable doubt".
This differs from the burden of proof in a civil trial, where the decision is based "on the balance of probabilities".