He was made a Labour minister in the Scottish Office department of the Blair Government as Parliamentary Under-Secretary of State for Scotland in 1997, where he assisted Donald Dewar in steering through the legislation that led to the creation of the Scottish Parliament. His name is given to the Sewel motion, parliamentary device passed by the Scottish Parliament, in which it agrees that the United Kingdom parliament may pass legislation on a devolved issue extending to Scotland, over which the Scottish Parliament has regular legislative authority. He left ministerial office in 1999 upon the new Parliament taking over the majority of the Scottish Office's functions. Sewel left the House of Lords in 2015 after being the subject of a drugs scandal.
Sewel was born on 15 January 1946. He was educated at Hanson Boys' Grammar School and Durham University (BA, 1967) before taking his MSc degree at University College of Wales, Swansea in 1970, and a PhD from the University of Aberdeen in 1977.
Sewel joined the University of Aberdeen as a research fellow in the Department of Politics in 1969. During the next three decades he worked in the Departments of Education and Political Economy and also the Regional Centre for the Study of Economic and Social Policy, where he was appointed to his chair. In 1988 he became the dean of the then Faculty of Economic & Social Sciences. Subsequently, in 1995, he was appointed vice-principal and dean of the faculty of Social Sciences & Law.
Sewel returned to the University of Aberdeen to resume his role as vice-principal in 1999 and was subsequently senior vice-principal from 2001 to 2004.
Sewel was first elected to political office as an Aberdeen District Councillor in 1974, serving as council leader from 1977 to 1980, and also as president of the Convention of Scottish Local Authorities from 1982 to 1984. Sewel was appointed a Commander of the Order of the British Empire (CBE) in the 1984 New Year Honours. Later, he was an influential member of the Scottish Constitutional Convention from 1994 to 1995.