Murder — Single count of murder — Where accused pleaded not guilty of murder but guilty of manslaughter — trial by judge alone.

Features of offending — gang violence — stabbing death by single stab wound — offence committed at Sydney Royal Easter Show — two groups of young males confronting each other in public — post-offence conduct of the accused — videos posted mocking the death of the deceased — relevance of disrespectful post-offence conduct to the s 23A(1)(b) test.

Manslaughter — alternative to murder — intention — what was the accused’s intention at the time he inflicted the stab wound — where Crown asserts that the accused had the intention to kill or cause grievous bodily harm — where the accused was affiliated with a gang and may have been motivated by a desire for revenge — where accused armed with a weapon at a public event — where accused had witnessed the fatal consequences of a stab wound previously.

Manslaughter — alternative to murder — excessive self-defence — whether the accused acted in excessive self-defence — whether the accused believed that his actions were necessary in the defence of himself or others in the circumstances as he perceived them — whether the accused observed the deceased to be a threat — whether the accused’s group were the aggressors — where PTSD impacted the accused’s perception of events.

Manslaughter — alternative to murder — substantial impairment — s 23A Crimes Act 1900 (NSW) — substantial impairment because of mental health impairment or cognitive impairment — whether the accused’s capacity to understand events, or to judge whether his actions were right or wrong, or to control himself, was substantially impaired by a mental health impairment or a cognitive impairment — whether the impairment was so substantial as to warrant liability for murder being reduced to manslaughter — application of community standards — factors relevant — young age and vulnerability of the accused — diagnosis of PTSD — accused’s history of involvement in gang activity and violence — lack of developmental maturity.

Witness evidence — eyewitness evidence — expert psychiatric evidence — where both psychiatric experts agree on mental health diagnosis but disagree on degree of impairment.