Recently sentenced offenders are transferred from court to a Correctional Service of Canada assessment unit, where they undergo the intake assessment process. At that stage, CSC officers gather all available information on the offender and use the tool you just referred to, the custody rating scale. As Mr. Wilkins said, that tool involves many factors, including the type of offence for which the offender is being incarcerated and the offender's inmate history, that is, his previous incarcerations. The inmate's incarceration history, at both the federal and provincial levels, is thus taken into consideration in the assessment using this tool, which is then used to suggest a security level.
We have to use the tool together with all available documents, such as police and court reports, and take into consideration victim concerns and harm done to victims, among other factors.
Security levels are reviewed during an offender's incarceration. These reviews are conducted using another tool, the security reclassification scale, which is completely different from the first tool used at intake when the offender's sentence begins.
The three main criteria used to assess an offender's security level are the risk within the walls, or level of institutional adjustment, the risk to the public and the risk of escape.