When the Wales Governance Centre reported that Wales has the highest rate of imprisonment in western Europe, and although the total number of prison sentences have risen in Wales between 2010 and 2017, they've fallen by 16 per cent in England, they said that wider research is needed to try to explain Wales's high rate of imprisonment. This is particularly relevant given that many of the services required to manage offenders, ex-offenders and promote rehabilitation are already devolved, raising questions about the comparative effectiveness of these devolved services, where, for example, the acting Prisons and Probation Ombudsman said last year that, unlike English prisons, Welsh prisons do not offer integrated drug treatment systems, and where we heard at lunch time, at the cross-party group on policing, that the Welsh Government's advisory panel on substance misuse has not met in the last year, or so we were told. What research is the Welsh Government, or has the Welsh Government commissioned, undertaken or accessed since this report to meet the call by the report's author, so that we have a better understanding of the true causes of this excessive imprisonment rate?