A sentencing judge must distinguish between an offender who acts with knowledge of what they are doing and one who possesses knowledge of the gravity of their actions; the former does not preclude a finding that the offender's appreciation of the gravity of their actions was diminished by mental disorder. Where unchallenged medical evidence establishes that mental disorder is causally related to the commission of offences and caused impairment of judgment and volitional control, the sentencing judge must moderate the consideration of general deterrence and assess what diminution should be applied to the sentence on account of the offender's reduced culpability. Merely varying the statutory ratio between head sentence and non-parole period may be insufficient to give effect to these principles.
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