O'Brien, Edward (1806–40), lawyer and writer, was born 6 December 1806 in Dromoland, Co. Clare, third son of Sir Edward O'Brien (1773–1837), 4th baronet and MP for Clare, 1802–26, and his wife, Charlotte, daughter of William Smith of Cahirmoyle, Co. Limerick. Edward's older brother was the Young Irelander William Smith O'Brien (qv); his younger sister was the anglican saint Harriet Monsell (qv). He was educated at Bewdley, Worcestershire, and at Trinity College, Cambridge, where he graduated BA (1829). After attendance at the Inner Temple and the King's Inns, he was called to the Irish bar (1832). In 1837 he was in London, in legal partnership with Woronzow Greig (1805–65), a Scottish barrister and friend of his brother William. On 15 August 1839 he married Louisa Susan, daughter of James Hewitt Massy Dawson but died nine months later, on 19 May 1840 at his sister's house, Whitkirk vicarage, near Leeds. He died of a fever, apparently caught as a result of over-exertion on behalf of Dublin charities. His son, Edward Arthur O'Brien (1840–1912) was born four months later, and his book The lawyer: his character and rule of holy life, after the manner of George Herbert was published two years later in 1842.
This book was distributed by Woronzow Greig and extravagantly well reviewed. It took the position that a lawyer's goal was the attainment of justice for the good of his fellow men. Through a series of scenes illustrating the moral dilemmas of a lawyer's life, it showed the various temptations he was prey to, such as avarice, dishonesty, and cunning, and how these could be overcome by cultivating a strong, inflexible conscience. The book's graceful style was much admired by Sir Aubrey de Vere (qv) and the Dublin University Magazine. The idealised lawyer depicted was supposed by his friends to be a self-portrait. O'Brien was everywhere eulogised as conscientious, cautious, Christian, and charitable. As a young man he had undergone a religious crisis, which strengthened his faith. To his brother William he was a devoted correspondent, though he did not share his interest in politics.