Justice Catherine McGuinness: When a law had been treated as valid for decades, it was impossible, unjust and contrary to the common good to reverse the many situations that had been affected over the decades, Ms Justice Catherine McGuinness said.
Allowing the appeal, she said that concluded proceedings based on an enactment subsequently found to be unconstitutional could not normally be reopened. This approach was in accordance with common law principles of finality in legal proceedings, she said.
She would not exclude exceptions to this normal rule but any such exception should be based on the clear demands of justice in the particular case.
"I do not consider that the present case on its facts is in any way such an exception," she said.
The applicant was convicted of an offence that consisted of sexual intercourse with a girl under the age of consent. At no stage had he denied that the act of sexual intercourse with the girl took place, she said.
There was no suggestion that he was denied due process in the course of the trial. He did not at the time challenge the constitutionality of the relevant section or take any of the other steps which might in law have been open to him, she said.
"The case was decided in accordance with the law applicable at the time and is not now open to attack," Ms Justice McGuinness said.
She said she agreed with the Chief Justice in what he had stated concerning the general principle governing criminal prosecutions where the State had relied in good faith on a statute in force at the time and concerning the application of those principles.
There was neither an express nor an implied principle of retrospective application of unconstitutionality in the Constitution, she said.
This conclusion was borne out by the case law relevant to the issue.
She referred to a judgment in another case which stated that what had happened had happened and could not, or should not, be undone.
Ms Justice McGuinnesss said that the passage outlined the general approach which must be taken to the application of retrospectivity in these circumstances and in particular represented the proper approach which should be taken to the present case.
"Can it seriously be said on the facts of the present case that the compulsion of public order and the common good would allow the application of the present applicant, Mr A, to succeed?" she asked.
A consideration of the case law as a whole demonstrated that, while the principle that the impugned statute or section was void ab initio was generally if not invariably set out, the actual outcome of the cases showed that what might be described as blanket retrospectivity had not in fact been applied, she said.
The facts of the cases differed and the reasoning for the conclusions may vary but it was impossible to establish either an express or an implied principle of unqualified retrospectivity, she said.
In common with Mr Justice Geoghegan, she agreed with the statement of Ms Justice Denham that a court was required to differentiate between the declaration of unconstitutionality and retrospective application of such a decision and that as a consequence it was a matter of construing the Constitution to determine how much a decision should be applied in a manner consistent with the principle of the Constitution, she said.
"I also agree that when a law has been treated as valid law for decades, it is impossible, unjust and contrary to the common good to reverse the many situations which have been affected over the decades," Ms Justice McGuinness said.