The 21 year old from Co Donegal, who cannot be named, pleaded guilty to the defilement of a child when he appeared at Letterkenny Circuit Court.
The man admitted the charge which took place at a vacant house in 2006.
He admitted the charge against a girl who was just 14 at the time while he was 15 and going on 16.
The court heard how the accused and another two boys and two girls entered the house after a ceili on August 5th, 2006.
The girl admitted that she took part in various acts of intimacy including performing oral sex on the boy.
However she denies she ever consented to ‘full sex’ with the boy.
The boy admitted having anal sex with the girl which she said he performed against her will.
The Gardai were informed of the incident when another girl told her father about the incident and he, in turn, informed the local school principal.
A full investigation was launched and the girl was taken to the Rotunda Hospital in Dublin for treatment.
The court heard that the young man had admitted to defiling the girl but claimed the sex was consensual.
The court heard that the girl had suffered from depression as a result of the incident and was on medication.
Barristers for the young man said the case had been hanging over him for six years as appeals were made to both the High Court and the Supreme Court.
The case attracted much notoriety in the media and became known as the Romeo and Juliet case because the law allows the prosecution of teenage boys for having sex with teenage girls but prevents prosecution of the girls.
Judge John O’Hagan said the case involved a couple of kids who got together and their hormones ran away with them.
He said the Oireachtas had clearly recognised that this was not a “sexual predator” type crime.
Judge O’Hagan said that perhaps he was too old to answer some of the questions thrown up by the case.
“The circumstances surrounding how it happened are quite different than perhaps what some of we older generation might have experienced.
“Young people have different views about experimenting with their bodies,” he said.
He added that he was not in any way blaming the young girl or suggesting she did anything wrong.
“On the other hand I am not suggesting (the man) did anything wrong in the heat of the circumstances of the moment,” he said.
Judge O’Hagan said that he had no plans to impose a custodial sentence on the young man.
Instead he sentenced him to six months in prison and suspended the term for a period of 12 months.
The young man’s mother wept in court as the sentence was passed down.