Dr Diarmuid Griffin holds a PhD from University College Dublin, an LLM and BCL from University College Cork as well as a teaching qualification from the University of Galway. In 2025, he published a sole-authored book, Sentencing Serious Sex Offenders: How Judges Decide when Discretion is Wide, with Policy Press. Early reviews of the book have described it as ‘timely and unique’, a ‘rich, multi-layered and nuanced work’ and ‘authoritative yet accessible’. He is also the author of Killing Time: Life Imprisonment and Parole in Ireland (Palgrave Macmillan, 2018).

Diarmuid’s research employs legal, criminological and empirical methodologies to shed light on the factors that influence criminal justice decision-making. His work has impacted the discourse in academia and his publications have been cited in many of the leading international journals (British Journal of Criminology, Theoretical Criminology etc). Diarmuid’s research has also contributed to the work of policy-makers and practitioners. His research has been cited by the Supreme Court of Ireland as well as being used as an evidence base for legal reform in the Houses of the Oireachtas. In 2019 he was awarded the President’s Award for Societal Impact for disseminating his research on parole to a wide audience and his advocacy work with NGOs and parliamentarians to reform the process. He has also provided workshops to life sentence prisoners on navigating the parole process.

Diarmuid is the Programme Director of the Law, Criminology and Criminal Justice degree, a programme he developed in 2019 to expand the discipline of criminology at undergraduate level. He has held visiting scholarships at the University of California, Berkeley, New York University and University of Toronto.

Current research interests include: Criminology, Criminal Justice, Sentencing and Punishment, Life Sentence Prisoners and Risk, Criminal Justice.

Current teaching duties includes: Criminal Law, Criminology, Criminal Justice, Crime and Disorder, Advanced Criminology.