The Effect of a Finding That Legislation is Unconstitutional: The Approach of the Irish Supreme Court

A number of common law jurisdictions permit the judiciary to strike down legislation which is inconsistent with that legal system's constitution. The Irish Constitution makes specific provision for this in Article 34.3.2°. The power to declare legislation invalid gives rise to a number of interesting questions concerning the temporal effect of such decisions. In Ireland, the courts have consistently adopted an approach whereby incompatible legislation which postdates the 1937 Constitution is deemed to have been void ab initio. Incompatible legislation originally passed by the British Parliament before 1937 is deemed not to have survived in Irish law from the date of the adoption of the Constitution. This gives rise to interesting issues surrounding the effect of past legal determinations which were based on such legislation. This problematic aspect of constitutional interpretation was considered at length by the Irish Supreme Court in the case of A v The Governor of Arbour Hill Prison (the ‘ A case’) in July 2006. This article explains the approach taken by the Irish courts to this aspect of constitutional interpretation and analyses the way in which the problem of legal effect was approached by the Supreme Court in the A case.