[1][2] He refused an offer to act as Crown Prosecutor after the Easter Rising.

[3] During his time as an elected official, O'Neill was criticised for "doing little to solve Dublin's dreadful housing problem".

[2] The problem could not be solved without generous government aid, which was not forthcoming, as the UK was involved in a world war.

[2] In an effort to retore peace during the 1922 Battle of Dublin, O'Neill chaired a committee of prominent women who met with military leaders on both sides.

He was elected to the Irish Free State Seanad Éireann at a by-election on 20 June 1929 to fill the vacancy caused by the resignation of Henry Petty-Fitzmaurice.