Sir David Dalrymple, 3rd Baronet of Hailes, (1726-1792), was the son of Sir James Dalrymple, 2nd Baronet of Hailes, and Lady Christian Dalrymple, daughter of the 6th Earl of Haddington. Sir David was educated at Eton and entered the Inner Temple in 1742. From 1747-1748 he studied Civil Law at Utrecht, and in 1748 was admitted to the Faculty of Advocates. He was raised to the Bench as Lord Hailes in 1766 and appointed a Lord of Justiciary in 1776. In addition to his legal activities, Lord Hailes had a wide variety of interests ranging from Scottish and British History, to Classical and literary studies, and Christian Antiquity, devotional and theological studies. Lord Hailes read widely, and was instrumental in setting up the Library at Newhailes. His interests are reflected here in his wide-ranging correspondence and extensive working papers which provided the basis for many of his numerous publications.
Lord Hailes was married twice, firstly to Anne Brown, daughter of Lord Coalston, and secondly to Helen, daughter of Sir James Fergusson, Lord Kilkerran.