The Supreme Court, by a three to two majority, has rejected claims by a former school teacher it would be unconstitutional to permit his prosecution for alleged offences of gross indecency against a male pupil between 1978-80 when the boy was aged between 15 and more than 17 years.
The case involved the juxtaposition of the modern understanding of the sexual exploitation of young people and a "notorious" law, Section 11 of the Criminal Law Amendment Act 1885, that was "a key part of a legal regime that caused so much misery to many homosexual men here" until its repeal in 1993, Ms Justice Iseult O'Malley observed.
Section 11 provided, inter alia, that "any" male who commits "in public or in private" an act of gross indecency with another male, "shall be guilty of a misdemeanour".
The Supreme Court had in 1984 dismissed a challenge by Senator David Norris to the constitutionality of Section 11 but the European Court of Human Rights later found the provision was contrary to the European Convention on Human Rights.
Section 11 was repealed in 1993 and replaced by an offence of gross indecency with a male under the age of 17 years.
There have been further reforms since in relation to offences of attempting to engage in sexual conduct with children under the ages of 15 and 17.
The DPP argued, as a result of the Interpretation Acts, it is still entitled in theory to bring prosecutions under Section 11 for historic offences committed before 1993.
It has undertaken there will be no prosecution of the teacher concerning any alleged offences committed after the boy turned 17.
After the Court of Appeal ruled the teacher lacked the necessary legal standing to argue Section 11 was unconstitutional, the Supreme Court agreed to hear a further appeal on the basis the case raised legal issues of general public importance.
It noted the alleged acts would have constituted criminal offences between 1978 to 1980 whether or not the complainant consented.
In the absence of consent, the applicant would also be prosecutable now on charges of buggery and indecent assault in respect of those acts committed at that time, it said.
There was no doubt such alleged activity today would constitute serious offences under the legislation that replaced Section 11 in 1993 or provisions enacted in 2006 but the question was whether it was constitutional to prosecute the applicant with gross indecency under Section 11, it said.
Three Supreme Court judges - Mr Justice Donal O'Donnell, Ms Justice Elizabeth Dunne and Mr Justice John MacMenamin - agreed the Constitution does not preclude the applicant's prosecution under Section 11 and dismissed his appeal.
The Chief Justice, Mr Justice Frank Clarke, and Ms Justice Iseult O'Malley, dissented.
In his judgment, Mr Justice O'Donnell said, while this area was "particularly emotive", it was important to separate the narrow legal issues which arise.
What is alleged against the applicant has always been regarded as a serious criminal offence punishable by law, he said.
The question whether it is appropriate to prosecute such matters 40 years later was for the DPP, not the court, he noted.
As a person accused of an offence under Section 11, the applicant has legal standing to argue the criminalisation of such conduct is invalid on grounds it breaches his constitutional rights, particularly to privacy, he said.
However, the applicant had not made that case and cannot now seek to challenge Section 11 on the basis, if utilised, it criminalised consensual sexual activity between others, he held.
Dissenting, Ms Justice O'Malley held the applicant has standing to challenge Section 11 on the basis it criminalises all sexual activity between men, whether in public or in private, regardless of age or consent, because the complainant was, by reference to the then law on sexual offences, to be treated as an adult.
It is not possible to apply current legislative standards on the protection of young persons to events that took place decades before those standards were introduced and an age of consent could not be read into Section 11 so as to bring it into compliance with the Constitution, she held.