Smith, Thomas Berry Cusack (1795–1866), attorney general, was born 15 November 1795, second son of Sir William Cusack Smith (qv), politician, judge, and baron of the Irish exchequer, and his wife, Hester, daughter of Thomas Berry of Eglish Castle, King's Co. (Offaly). Thomas followed his father in choice of career and in assuming a matronymic. Graduating BA from TCD (1813), he entered Lincoln's Inn in 1817, was called to the Irish bar two years later, and took silk in 1830. That year he published, with Espine Barry, Reports of cases in the court of king's bench in Ireland, 1824–5. In the general election of 1835 he stood as a conservative for Youghal against John O'Connell (qv), son of Daniel O'Connell (qv), and was beaten by seven votes. He was appointed solicitor general on 22 September 1842 and was immediately put forward as the government candidate for the Dublin University constituency, where a vacancy had arisen. However, the university tories nominated George Alexander Hamilton, an opponent of the national education system, and Smith had to withdraw, to the chagrin of the home secretary, Sir James Graham, who regarded this as an evil omen. Smith was shortly afterwards made Irish attorney general (4 November 1842–26 January 1846) and sat in the commons as tory member for Ripon (March 1843–January 1846).
His tenure was difficult; he held office during the period of O'Connell's monster meetings, and the home secretary became increasingly impatient with him for not instituting proceedings against the repeal press, while Peel told his cabinet in July 1843 that the arms bill had been badly drafted and that Smith was proving a disappointment. The arrest of O'Connell and eight ‘traversers’ in October 1843 delighted Smith. He had a personal grudge against O'Connell, who had attempted to have his father's conduct as a judge censured in 1834, and he took pleasure in exacting filial revenge by conducting the prosecution in a celebrated trial, which ran until summer 1844. However, he did not find the outcome satisfactory, as O'Connell's initial conviction was overturned in the house of lords. Smith's statement of the case occupied two days, during which he spoke for twelve hours, but he relied on well-known speeches and articles of O'Connell's and had no new evidence, and his delivery was poor. One of the traversers described his speech as ‘Drip, drip, like water from a rusty pump the familiar facts fell from his lips’ (Nation, 20 Jan. 1844). However, Peel considered Smith's speech in the house of commons in 1844, defending his action in the O'Connell prosecution, as one of the three speeches most effective for their immediate purpose which he had ever heard. In the course of the trial Smith lost his temper and challenged Gerald Fitzgibbon, one of the opposing counsel, to a duel; the judges intervened and Smith had to apologise, causing the home secretary to comment that ‘nothing can be done in Ireland without a blunder, when Irishmen alone are employed’ (Gash, 407). This incident may have cost Smith the Irish chancellorship.
Charles Gavan Duffy (qv) put Smith's famed irascibility and his ‘meagre, unwholesome and ghastly’ appearance (Duffy, 392) down to a bad digestion; O'Connell simply nicknamed him ‘Alphabet Smith’ and ‘the Vinegar Cruet’. On quitting the attorney generalship Smith was made master of the rolls in Ireland in 1846, a post where he acquitted himself well and which he held until his death, which took place suddenly at his shooting lodge at Blairgowrie in Scotland on 13 August 1866. He was survived four years by his wife, Louisa (m. 1827), daughter of James Hugh Smith-Barry of Marbury Hall, Cheshire, and of Fota, Co. Cork, and was also survived by a son.