Along with Arthur Griffith, Michael Collins and Eoin O'Duffy, O'Higgins is an important figure in Irish nationalist historiography, representing a more "conservative revolutionary" position when contrasted with republicanism.

In the debate that took place in the Dáil on the Treaty, O'Higgins outlined the reasons for his support thus: Last October the Minister of Local Government W. T. Cosgrave and myself came deliberately to the decision that we would not recommend any settlement involving allegiance to the King of England.

But I face the political situation and realise that some of the biggest personalities in our movement ... have considered this is the last ounce [that] could be got from England, and who, knowing the situation better than I do, attached their names to that document.When running for election in 1922, he told a crowd: I have not abandoned any political aspirations to which I have given expression in the past, but in the existing circumstances I advise the people to trust to evolution rather than revolution for their attainment.He was duly elected as a TD for Leix–Offaly, becoming Minister for Justice and External Affairs in the Provisional Government.

The contemporary Labour Party leader Tom Johnson said the executions were "utterly to destroy in the public mind the association of the Government with the idea of law.

[7] On 11 February 1923, the Anti-Treaty IRA killed his father, who had snatched a revolver from the leader of a raiding party in his family home in Stradbally, County Laois.

O'Higgins feared, as did many of his colleagues, that a prolonged civil conflict would give the British an excuse, in the eyes of the world, to reassert their control in the Free State.

O'Higgins had formed a negative view of Cosgrave, having worked under him at Local Government, and was not happy when the latter was appointed President of the Executive Council.

Of the alternatives Mulcahy had been seen as indecisive, pedantic and too close to the Army (opinions which the subsequent Kenmare incident would make widespread), whereas O'Higgins himself was not avowedly republican.

In the Government of the 3rd Dáil, he would be classed, along with Desmond FitzGerald, as one of the “Donnybrook set" – out of step with the rest on issues such as Irish language, autarky and militarism.

[8] In March 1924, midway through the 'Army Mutiny', Minister Joseph McGrath resigned from the cabinet and President Cosgrave took sick leave.

O'Higgins, as de facto head of government, reversed Cosgrave's policy of appeasement and confronted the IRAO mutineers confounding their objectives.

Though far-left political enemies characterised him as having supposed "fascist" tendencies, O'Higgins was to the fore in resisting the small wing of Cumann na nGaedheal who looked to Italy for inspiration.

[11] He did not approve of feminism, for instance when asked by Leader of the Labour Party Thomas Johnson in the Dáil whether he believed giving women the vote had been a success, O'Higgins replied, "I would not like to pronounce an opinion on it in public".

[14] Harry White, the former IRA chief of staff explained the cause of the assassination as; "As minister for justice, he ordered the murder of his former friends, Rory O’Connor, Liam Mellows, Dick Barrett and Joe McKelvey in Mountjoy Jail .. That’s why he was killed."

None of the three assassins was ever apprehended or charged, but Coughlan, a member of Fianna Fáil as well as the IRA, was killed in strange circumstances in Dublin, in 1928, by a police undercover agent whom he was attempting to murder.

Gannon, who died in 1965, joined the Communist Party of Ireland and played a central role in organising Irish volunteers for the Spanish Civil War.

[17][18] In 1927, a relief of O'Higgins was posthumously added to a 1923 cenotaph in the grounds of Leinster House dedicated to Michael Collins and Arthur Griffith.