Mental illness and sentencing

R. v. Prioriello, 2012 ONCA 63 deals with when mental illness is a mitigating factor in sentencing.  The Court holds:

[11]. In order for a mental illness to be considered as a mitigating factor in sentencing, the offender must show a causal link between his illness and his criminal conduct, that is, the illness is an underlying reason for his aberrant conduct:  R. v. Robinson, [1974] O.J. No. 585 (C.A.).