TEENAGE boys can continue to be prosecuted for underage sex while teen girls are exempt.
The 'Romeo and Juliet' law is constitutionally sound because it reflects a girl's risk of pregnancy after sex, the Supreme Court ruled yesterday.
The court also said that it was not always possible to apply the same treatment to everyone, especially when it came to different genders.
It stemmed from a 15-year-old boy being charged with having sex with a 14-year-old girl in Donegal on August 5, 2006.
The boy was also charged with buggery and his trial was on hold pending the outcome of yesterday's Supreme Court ruling.
It is alleged the boy and girl engaged in consensual oral sex having just met the day before.
The girl claims that sexual intercourse and buggery took place as a result of force and fear. He disputes this and says all the sexual activity was consensual.
He was charged with having underage sex with the girl under the Sexual Offences Act 2006.
Section five of this act states that a girl under the age of 17 will not be guilty of an offence by reason only of her engaging in an act of sexual intercourse.
When he took a challenge to his prosecution in the High Court, he claimed he was being discriminated against on grounds of gender.
His lawyers argued that his constitutional and European Convention rights had been breached. The High Court dismissed the challenge.
Upholding that decision yesterday, the Supreme Court also awarded the costs of taking the case against the State and the DPP.
The court unanimously ruled the law was constitutional, because lawmakers could take account of the danger of pregnancy for teenage girls in such cases.
They could give regard to this in relation to "differences of capacity, physical and moral and social function" as provided for in Article 40.1 of the Constitution.
Laws prohibiting discrimination on grounds of pregnancy have also applied to women, but laws such as these are not examples of the State holding men and women unequal before the law, said Chief Justice Susan Denham.
While strict equality is the norm laid down by Article 40.1 of the constitution, it also recognises that perfectly equal treatment is not always achievable, Ms Justice Denham said.
She said that it recognises that applying the same treatment to all is not always desirable because of the different circumstances in which people find themselves.
Some of these differences between people are most obvious in cases affecting the different sexes.
The court also rejected arguments on behalf of the boy in relation to his European Convention rights to a private life, including a sexual life, and his right to a fair trial on grounds of gender.
The court said in view of the special circumstances of the case -- including that it concerned social policy and that the boy was a minor -- the normal rule that the loser pays the costs would not apply.