Where a sentencing judge finds that an offender's mental disorders substantially contributed to the offending, this results in a corresponding reduction in moral culpability and calls for significant moderation of the sentence. For child offenders convicted of murder, the standard sentence regime does not apply, and the mitigatory effect of youth will be extinguished only in circumstances of the gravest criminal offending where there is no realistic prospect of rehabilitation. A total effective sentence of 20 years for a 15-year-old with undiagnosed autism spectrum disorder and major depressive disorder who pleaded guilty to murder and two counts of attempted murder was manifestly excessive; 16 years with an 11-year non-parole period was substituted.
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