Dr Mannion is a consultant psychiatrist and former Clinical Director with the HSE. She is a member of the College of Psychiatrists of Ireland and a Fellow of The Royal College of Psychiatrists.
She has an extensive clinical background, has been a Senior Lecturer in Psychiatry in NUIG, with ongoing involvement in training of Psychiatrists with the COPI. She was appointed as a member of the non-statutory Parole Board in 2017.