New Courts System
Westminster passed the Irish Free State (Constitution) Act, 1922, which repealed the Government of Ireland Act, 1920 in so far as it applied to Southern Ireland. The Dáil enacted the Constitution of the Irish Free State (Saorstát Éireann) Act, 1922, implementing the Irish Free State Constitution, which was based on the terms of the Treaty. The Constitution enshrined the separation of powers between the executive, legislative and judicial arms of government. On the judicial side, a Supreme Court, High Court and courts of local and limited jurisdiction were established. The Constitution provided a right of appeal from Irish courts to the Judicial Committee of the Privy Council.

The transition to the new court system was complicated by the fact that two court systems had been in operation since 1920: the ordinary court system and the 'Dáil courts'. The latter comprised the Parish Court, which dealt with the most minor civil and criminal matters, the District Court, which dealt with more serious civil and criminal matters and which heard appeals from the Parish Court, a Circuit Court composed of four circuits, with unlimited civil and criminal jurisdiction and a Supreme Court, operating as both a court of first instance and an appellate court. While successfully suppressed by the British in Dublin, these courts operated with some success elsewhere. Following the signing of the Treaty, the Dáil wound up these courts and adopted the court system created under the 1920 Act. The courts established pursuant to the Free State Constitution later held that decisions of the Dáil courts were void in law (see R (Kelly) v Maguire [1923] 2 I.R. 58).

In January 1923 the Judiciary Committee, chaired by former Lord Chancellor Lord Glenavy, was appointed to advise the Executive Council (Cabinet) on the establishment of a new court system. The Committee's recommendations were substantially adopted in The Courts of Justice Act, 1924. It created a District Court to replace the court of petty sessions and the Justice of the Peace. The Justices of the District Court were professional judges and had jurisdiction over minor civil and criminal matters. The Circuit Court had jurisdiction in more serious civil and criminal matters. On the civil side, it replaced the county court, and on the criminal side, it assumed the former jurisdiction of the court of assize. It had appellate jurisdiction over District Court cases. A High Court exercising the same jurisdiction as that proposed under the 1920 Act was created. On the criminal side, the most serious offences, such as murder, were reserved to it. The court was to be presided over by a President of the High Court. A Court of Criminal Appeal to hear appeals from the Circuit Court and High Court was also established. Provision was made for a further right of appeal to the Supreme Court on a point of law of exceptional public importance. The Supreme Court was created as the final court of appeal, to be presided over by the Chief Justice.