Ronald David Mackay, Lord Eassie, PC (born 1945) is a Scottish lawyer and retired judge of the country's Supreme Courts, sitting in the Inner House of the Court of Session.

Mackay was educated at Berwickshire High School in Duns, Scotland,[1] and studied at the University of St Andrews (M.A.

[2] Mackay was appointed Queen's Counsel in 1986, serving as a prosecutor in the Crown Office and Procurator Fiscal Service until 1990.

[2] In 1997, Mackay was appointed a Senator of the College of Justice and assumed the judicial title of Lord Eassie.

[5] Lord Eassie resigned his position on the Law Commission in order to serve on the Inner House of the Court of Session.