Fergus is a graduate and former scholar of Trinity College, University of Dublin, from which he holds an LLB (Hons) and a PhD. He is a law lecturer with many years' experience teaching and researching law, with a particular focus on family law, constitutional law and human rights. From 1998 to 2013, Fergus taught at the Dublin Institute of Technology, at which he served as Head of the Department of Law from 2003 to 2009 and again in 2013. Fergus has also been a visiting lecturer at the School of Law, Trinity College, Dublin (2002-5), teaching Family Law, at UCD, and at the Law Society of Ireland. Since 2001 he has served as internship director for the University of Tulsa College of Law Summer Abroad programme in Dublin, placing over 200 interns during this period. In 2011, he was a visiting scholar in Child and Family Law at the Children and Family Law Center at Washburn University School of Law, Topeka, Kansas.
Fergus' publications include (with Dug Cubie) Immigration, Refugee and Citizenship Law in Ireland: Cases, and Materials (Round Hall 2004); (with Judy Walsh), The Rights of De Facto Couples, (IHRC 2006); Contract Law (Round Hall 2006); Constitutional Law (Round Hall 2008); Civil Partnership: Your Rights Explained (GLEN, 2009); and The Civil Partnership and Certain Rights and Obligations of Cohabitants Act 2010 (Round Hall 2011). Fergus has also published several academic articles and book chapters, including a chapter in Leane and Kiely (eds.) Sexualities and Irish Society: A Reader (Orpen Press, 2014).
Fergus has advised the Equality Authority, the Irish Human Rights Commission and the Law Reform Advisory Committee of Northern Ireland on issues of family law and human rights. He has also written and spoken widely on family law issues, in particular civil partnership and cohabitation, and appears regularly on national and local TV and radio speaking about a variety of legal issues. Fergus is currently the President of the Irish Association of Law Teachers, a position in which he previously served from 2003-4. He is the Irish representative on ECSOL (the European Commission on Sexual Orientation Law).