An IT error in a system used by Scotland's criminal justice service to help set risk levels for use in sentencing and prison release decisions resulted in the wrong risk level being attributed to hundreds of Scottish offenders.

The Level of Service and Case Management Inventory (LS/CMI) is a general risk assessment tool (pdf) that draws on several dozen assessment factors to categorise prisoner risk into five categories, from 'Very low' to 'Very high'. 

It has been used by social workers and prison staff in all 32 Scottish authorities since November 2021.

Officials discovered that the system was failing to update its assessment when new information about an individual had been entered. As a result, risk scores were incorrect for 495 'closed' cases and for another 285 'open' cases.

The incident resulted in eight of Scotland's worst offenders serving life for murder or rape being released from jail early, and the possibility that hundreds of others had been freed in error, resulting in a political controversy and an apology from Scotland's Justice Secretary.

Social workers were told to switch to a paper-based system while the problem was resolved.