Justice Donnelly is an Associate Justice of the Ohio Supreme Court. Prior to joining the state Court, Justice Donnelly served as a judge on the Cuyahoga County Court of Common Pleas, General Division for 14 years. In addition, from 2010 to 2017, he was one of five judges on Cuyahoga County's Mental Health and Developmental Disabilities Court, which oversees criminal cases involving defendants who suffer from severe mental illness or developmental disabilities. Before serving as a member of the local judiciary, Justice Donnelly was an assistant Cuyahoga County Prosecutor from 1992 until 1997. Justice Donnelly has also been a faculty member of the Ohio Judicial College.