[1] Following the killing of his father and his brother during the Irish Civil War in the 1920s, he became politically radicalised and joined Cumann na nGaedhael, as well as also briefly becoming the leader of the Blueshirts.

O'Higgins grew up in Stradbally, County Laois, the second son of sixteen children (eight boys, eight girls) of Dr. Thomas Higgins and Anne Sullivan.

As a result, he was sent to Abercorn Barracks in County Down, during which time his home back in Portlaoise was turned into an Officers' Mess for the Black and Tans after they evicted his wife and children.

During the Civil War Kevin, as Minister for Justice, had brought in severe measures to crack down on the IRA, including the introduction of the death penalty.

Fianna Fáil had been pressured to drop their abstentionism partially after Kevin O'Higgins as Minister for Justice brought forward a law that requiring all political candidates to swear that they would take the Oath of Allegiance if elected to the Dáil.

Upon entry into government, Fianna Fáil set about releasing many of the political prisoners arrested by Cumann na nGaedhael in the preceding years.

Frank Ryan, one of the most prominent socialists in 1930s Ireland, active in the IRA and Republican Congress, declared "as long as we have fists and boots, there will be no free speech for traitors".

O'Higgins was joined in the organisation by fellow Cumann na nGaedhael TDs Ernest Blythe, Patrick McGilligan and Desmond Fitzgerald.

[5] It was under O'Higgins direction that the ACA went from an association of ex-National Army members into a crusading right-wing movement hitched to Cumann na nGaedhael.

O'Duffy took the ACA into a more radically hardline direction, renaming it the "National Guard" and adopting many elements of European Fascism such as the Roman straight-arm salute, uniforms and huge public rallies.

In response, O'Higgins and Desmond FitzGerald led other Fine Gael TDs in wearing the blue shirt of the National Guard in the Dáil chamber.

In February 1934, at Fine Gael's first national convention, O'Higgins denounced Fianna Fáil as ‘the vanguard of the communist policy here’, and called Éamon de Valera an ‘arch-communist agent’.

O'Higgins was amongst the Fine Gael leaders more open to the introduction of Corporatism policies being pushed by members of the Blueshirts such as James Hogan, Michael Tierney and Ernest Blythe.

[2] During World War II, O'Higgins defended the right of James Dillon to speak out against the party's stance of supporting Irish neutrality alongside Fianna Fáil.