Arthur Blennerhassett (1687–1758)
Arthur Blennerhassett KC (1687–3 January 1758) was an Anglo-Irish lawyer, politician and judge. He is best known for killing John St Leger in a duel, though he was later acquitted of murder.
He was the only son of Robert Blennerhassett of Clonmel and Alice Osborne. He studied in Dublin and graduated from Trinity College, Dublin in 1708, the same year he joined the Middle Temple. He was called to the Irish Bar in 1714, became a King's Counsel in 1728, and served as Prime Serjeant in 1742.
In 1727 Blennerhassett was elected to the Irish Parliament asMP for Tralee. He was raised to the bench as a justice of the Court of King's Bench (Ireland) in 1743 and served until his death in 1758. In 1745 he was one of the judges at the perjury trial arising from the Annesley Peerage Case; the proceedings were long and exhausting, and he collapsed, leaving the Chief Justice to continue.
He married twice, first Mary Pope and then Mary Rice; he had no children. He lived on Dawson Street in Dublin and at Riddlestown Park in County Limerick, which he inherited from his uncle Edward Blennerhassett and improved.
According to Elrington Ball, Blennerhassett was accused but acquitted of the murder of John St Leger, who he killed in a duel in 1741. Such duels rarely led to murder convictions among the aristocracy, and the killing did not damage his reputation or career. A portrait of the judge hangs in the library at Glin Castle.
This page was last edited on 2 February 2026, at 17:29 (CET).