He was grandson of Sir Michael Smith, 1st Baronet, Master of the Rolls in Ireland from 1801 to 1806 and his first wife Maryanne Cusack.
[2] His conduct of the trial attracted severe criticism, and the House of Lords later quashed the guilty verdict due to gross irregularities in the proceedings.
[4] He became Master of the Rolls in Ireland in 1846, holding that office until his death, which occurred at Blairgowrie and Rattray in Scotland.
[2] Like his father he had a reputation for eccentricity and bad temper: during the trial of Daniel O'Connell he challenged one of the opposing counsel, Gerald Fitzgibbon, to a duel, for having allegedly accused him of acting from "private and dishonourable motives".
The judges, gravely embarrassed, strongly criticised Cusack-Smith for his actions and persuaded him to drop the matter.