Deasy, Rickard Morgan (1812–83), MP, lawyer, and judge, was born 23 December 1812 in Clonakilty, Co. Cork, second son of Rickard Deasy and Mary-Anne Deasy (née Caller). He entered TCD in 1829 and graduated in 1833. After a distinguished, deeply studious, collegiate course he was called to the Irish bar (1835) and immediately won judicial respect for lucid and systematic presentation on the Munster circuit. As usual, nevertheless, it took some years to make a professional breakthrough there and in the courts of equity, his chosen specialisation. His generation established itself on circuit by the early 1840s, his conduct of cases being noted for a tenacious, earnest identification with clients. He also applied himself to academic study and reflective writing on political and other matters in serious contemporary periodicals. Appointment to QC (1849) was an endorsement of the cautious advancement of catholics within the legal establishment, and widened his chancery practice.
Though not of innate political temperament, he was cajoled by friends to contest the Co. Cork by-election as a Liberal (April 1855) on the resignation of his friend Lord Fermoy, and he defeated Vincent Scully (qv) in a tight contest. Under the administrations of Lord Palmerston, he was appointed third serjeant at law (1858–9), solicitor general for Ireland (June 1859–February 1860), and attorney general for Ireland (February 1860–January 1861). Impeccable moderation in debate (together with a commendably businesslike parliamentary style) endeared him to conservatives though he was himself ‘Liberal’, and did no harm to his legal prospects. His major achievement in parliament was the codification of Irish property legislation in the Landlord and Tenant Law Amendment Act (Ireland), 1860 (generally known as Deasy's act), which simplified matters firmly in favour of the landed interest. He left parliament in 1861 on being made fourth baron of exchequer (1861), one of several appointments of catholics to the Irish bench made by the Liberal government. In 1878 the tory government bypassed party interest to appoint him lord justice of appeal, a mark of unusual confidence. He died at 41 Merrion Sq., Dublin, on 4 May 1883 and was buried in Deansgrange cemetery.
He married (1861) Monica O'Connor (d. March 1883); they had three children, two of whom predeceased their parents.