This paper examines the natural law jurisprudence of the Irish High Court and Supreme Court since the founding of the Irish State to the present day. This jurisprudence includes the leading cases on such controversial issues as the right to contraception, the criminalisation of male homosexuality and whether abortion was prohibited by the Irish Constitution. The paper shows that the case-law contains different lines of judicial thought on how to interpret those parts of the Constitution which refer to God and natural rights ‘antecedent and superior to positive law’. It argues that there were two main strands in the case-law: the ‘Christian’ strand, which emphasised the importance of Christian values and even Catholic social and moral teaching when interpreting the Constitution, and the ‘dignitarian’ strand which emphasised the dignity and freedom of the individual and the more secularised ideal of justice. The latter strand has gained dominance on the Irish Supreme Court since the 1990s. (Note: ‘Oireachtas’ means Parliament and ‘Bunreacht na hEireann’ means Basic law of Ireland ie the 1937 Irish Constitution).