Stewart was born in Campbeltown and educated at Dalintober Primary School and the Edinburgh Academy.
[1] He studied at Balliol College, Oxford (BA), and the School of Law of the University of Edinburgh (LL.B.)
He edited two of the four volumes of the Faculty of Advocates Minute Book, published in 1999 and 2008 respectively by the Stair Society.
[3] He was Senior Advocate Depute from 2005 to 2007 and Leading Counsel to the Billy Wright Inquiry in Northern Ireland, from 2008 to 2010.
[2] The inquiry, chaired by Scottish judge Lord MacLean, investigated claims of collusion between prison authorities and the paramilitary Irish National Liberation Army in the death of Loyalist Volunteer Force leader Billy Wright in the Maze Prison in 1997.