Ewing was educated at Edinburgh University and worked at Cambridge University in England, Monash University in Australia, Osgoode Hall in Canada, before joining the King's College London law school in 1992.
Ewing is recognised as a leading scholar in public law and labour law. He has written extensively on the funding of political parties. Ewing has been regarded as "the most prolific and influential scholar in political finance in the common law world beyond the US". His first book on the topic was published in 1987 (The Funding of Political Parties in Britain by Cambridge University Press).
Ewing's scholarly legacy was celebrated "as one of the world's leading scholars of the constitution of social democracy". Papers in his honour will be published in a book for Hart-Bloomsbury in 2020, edited by Professor Alison Young (Cambridge University), Professor Alan Bogg (Bristol University), and Professor Jake Rowbottom (Oxford University).
His most recent work relates to reforming labour law to strengthen trade union freedom, constitutional reform, relating to public participation in the political process and the status of social and economic rights..
- 'What today's charter of workers' rights looks like' (31 January 2011) The Guardian
- A Manifesto for Labour Law (2016)
- (with Jacob Rowbottom and Joo-Cheong Tham) The Funding of Political Parties: Where Now? (Routledge 2011)
- The Bonfire of the Liberties (Oxford University Press 2010)
- (with AW Bradley) Constitutional and Administrative Law (Longman 2007)
- The Cost of Democracy: Party Funding in Modern British Politics (Hart Publishing 2007)
- (with Samuel Issacharoff) Party Funding And Campaign Financing in International Perspective (Hart Publishing 2006) Columbia-London Law Series
- (with Hugh Collins and Aileen McColgan) Labour Law, Text, Cases and Materials (Hart Publishing 2005) ISBN 1-84113-362-0
- (with Tom Campbell and Adam Tomkins) Skeptical Essays on Human Rights (Oxford University Press 2002)
- (with Conor Gearty) The Struggle for Civil Liberties (Oxford University Press 2000)
- Money, Politics and Law: A Study of Electoral Campaign Finance Reform in Canada (Clarendon Press 1992)
- (with Conor Gearty) Freedom under Thatcher: Civil Liberties in Modern Britain (Oxford University Press 1990)
- Britain and the ILO (1989)
- The Funding of Political Parties in Britain (Cambridge University Press 1987)
- King's Law School staff page
- Orr, Graeme (2018). "The Law of Electoral Democracy: Theory and Purpose". SSRN Electronic Journal. doi:10.2139/ssrn.3253795. ISSN 1556-5068.