Andrew Ashworth, Q.C., is Vinerian Professor of English Law, University of Oxford and a Fellow of All Souls College. He is the author of Sentencing and Criminal Justice (5th edn.,, Cambridge University Press). Other recent volumes include Principled Sentencing (3rd edn., with A. von Hirsch and J.V. Roberts) and Proportionate Sentencing (Oxford University Press, with A. von Hirsch). He teaches sentencing courses at the University of Oxford. Julian V. Roberts is a Professor of Criminology in the Faculty of Law, University of Oxford. Sentencing has been his principal area of research and teaching since 1984. Recent books include: Mitigation and Aggravation at Sentencing (Cambridge University Press, 2011); The Role of Previous Convictions at Sentencing (Oxford: Hart Publishing, with A. von Hirsch); Punishing Persistent Offenders (2008, Oxford University Press); Principled Sentencing (with A. von Hirsch et al., 2009; Oxford: Hart). Roberts teaches sentencing courses at the University of Oxford.