The Restoration of Order in Ireland Act 1920, an Act of the Parliament of the United Kingdom to address the collapse of the British civilian administration in Ireland during the Irish War of Independence, receives royal assent on August 9, 1920, following a guillotine motion.

In effect a special extension of the Defence of the Realm Acts, the aim of the Act is to increase convictions of nationalist rebels while averting the need to declare martial law. Under Section 3(6) of the Act, military authorities are empowered to jail any Irish person without charge or trial. Secret courts-martial are established, and lawyers (appointed by Crown agents) can be present only if the death penalty is involved. Inquests of military or police actions are banned.

By the middle of 1920, Ireland is in the throes of a full-fledged rebellion that is barely recognized by the British Government in Ireland headquartered in Dublin Castle. The Irish Republican Army (IRA), the military arm of the Dáil Éireann revolutionary government, is engaged in a guerilla campaign to destroy elements of British power, particularly burning down courthouses and attacking members of the Royal Irish Constabulary (RIC), Britain’s police force in the countryside.

The British response to the increase in violence and the assassination of police officers is twofold. To suppress the IRA “murderers,” Major General Hugh Tudor, commander of the RIC and self-styled “Chief of Police,” begins supplementing that body with the employment of World War I veterans known as the “Black and Tans” because of the colour of their surplus World War I uniforms, and an additional temporary force of Auxiliaries. With little discipline and utter indifference to the plight or moral indignation of the Irish population, these groups raid and burn villages, creameries, and farm buildings to intimidate supporters of the IRA.

The second measure is the enactment of the Restoration of Order in Ireland Act (ROIA). The Act is envisioned as a remedy to the problem perceived by Chief Secretary for Ireland Sir Hamar Greenwood that “throughout the greater part of Ireland criminal justice can no longer be administered by the ordinary constitutional process of trial by judge and jury.”

The genesis of the Act may be seen in a Cabinet discussion on May 31, 1920, in which the members focus on the violence in Ireland. Rather than addressing violence as the product of rebellion, Greenwood insists that, “The great task is to crush out murder and arson.” He asserts that the violence is perpetrated by handsomely paid thugs. Commenting on a pending Irish bill, Secretary of State for War Winston Churchill states, “You should include in the Bill a special tribunal for trying murderers. It is monstrous that we have some 200 murders, and no one hung.” The prime minister agrees that convicted murderers should be hanged but questions whether convictions can be obtained from Catholics. The concern of all is that the civil courts are incapable of strictly administering justice to the revolutionaries because the juries largely consisted of Irish Catholics. The ensuing discussion of possibly imposing court-martial jurisdiction is inconclusive.

After the May 31 meeting, Greenwood investigates the feasibility of imposing martial law in Ireland and raises martial law as the specific subject of a July 23, 1920, conference committee meeting of the Cabinet led by Prime Minister David Lloyd George to which the key members of the Dublin Castle administration are invited. William E. Wylie, the law advisor at Dublin Castle, notes that the RIC is disintegrating through resignations brought on by terrorist attacks, and that with “regard to the Civil Courts, the entire administration of the Imperial Government had ceased.” The civilian participants from Dublin Castle, especially Wylie, maintain that martial law is counter-productive, and will only antagonize the Irish people. As an alternative to martial law, General Tudor argues for the imposition of court-martial jurisdiction. Tudor argues forcefully that court-martial jurisdiction over all crimes will support the Black and Tans and Auxiliaries that he is recruiting. He declaims that “not a single criminal had been brought to justice for murder.” Lloyd George closes the discussion directing the Dublin Castle participants to provide final proposals for enforcement of the laws.

A draft bill to establish military criminal jurisdiction is considered by the Cabinet on July 26. The prime minister’s most telling contribution is his question as to whether a convicted man would be shot or hanged. It appears that he is comforted by the response that the defendant will be tried under the ordinary law which implies death by hanging. The resulting bill is completed by July 30, 1920, and is then quickly pushed through Parliament and receives royal assent on August 9, 1920. The ROIA provides that all crimes punishable under the laws in Ireland can be brought before a court-martial. The court-martial will have the power to impose any punishment authorized by statute or common law including the death penalty. The final step is taken on August 20, 1920, when the final regulations for implementation go into effect.

The combination of growing police and military pressure and recourse to the ROIA lead to increased internments of known or suspected IRA members and a steady increase in convictions to 50-60 per week. This makes it more difficult for IRA soldiers to continue openly working day jobs while carrying on part-time guerrilla activities. As a result, the IRA shifts its approach to guerrilla warfare in the rural counties. Volunteers from IRA units are organized into elite, full-time, mobile flying columns of around 25 men who live off the land and on the run. These flying columns prove to be more suited to ambushes of patrols and convoys and other targets of opportunity, rather than attacks on barracks which had become better defended.

On December 10, 1920, martial law is proclaimed in counties Cork, Kerry, Limerick, and Tipperary. In January 1921 martial law is extended to counties Clare and Waterford.

In a crucial judgement, R (Egan) v Macready, the Irish courts rule that the Act does not give power to impose the death penalty. This would no doubt have proved politically contentious had not hostilities ended the same day.

Despite its name, the courts are of the view that ROIA applies in England as well. Following the creation of the Irish Free State, when the Act is repealed by implication, it is still used to deport ex-members of the Irish Self-Determination League to Ireland.