Professor Walsh graduated with an LLB from Queen’s University Belfast in 1980. He was the first holder of the Cobden Trust Studentship on emergency law in Northern Ireland. He was called to the Bar of Northern Ireland in 1983 and took up a Lectureship in Law in University College Cork in the same year. He was appointed to a Senior Lectureship in Law in the University of Ulster in 1992 and Chair in Law at the University of Limerick in 1996. He was awarded a Government of Ireland Senior Research Fellowship in 2007 and was elected a Member of the Royal Irish Academy in 2011. He took up his current position of Professor of Law at the University of Kent in 2013. He is a former President of the Irish Association of Law Teachers.
Professor Walsh specialises in policing, criminal procedure and EU criminal law, with a particular emphasis on due process, accountability, transparency and human rights. He has published extensively in these areas, including the leading texts: Walsh on Criminal Procedure 2nd ed (2016) and The Irish Police (1998).