Lack of defence of honest mistake renders unconstitutional the offence of unlawful carnal knowledge.

Fennelly J (Full text.): Constitutionality of statute - unlawful carnal knowledge - defence of honest mistake - s 2, Criminal law (Amendment) Act, 1935 - charge of unlawful carnal knowledge with 16-year-old girl - whether amendment to s 2 by Criminal Law Act 1997 conferred presumption of constitutionality on section -lack of presumption of constitutionality on pre-1937 legislation - distinction between re-enactment and mere amendment - whether Oireachtas intended to exclude defence of mistake.

Denham CJ (Full text.): Whether amendment of section by 1997 Act was a re-enactment conferring presumption of constitutionality on section - whether amendment was an enactment with substantive effect - whether section vested with status of post-1937 enactment.

Murray J (Full text.): Expansion of s 2(1), Criminal Law (Amendment) Act 1935 by s 2, Sexual Offences (Jurisdiction) Act 1996 - application of section to offences committed outside the jurisdiction - whether s 2(1), as amended, fell to be treated as post-1937 legislation - Article 34.4.5, Bunreacht na h-Eireann - requirement that decision of Supreme Court on validity of a law be unanimous.