Substantial Impairment due to Mental or Cognitive Impairment

Introduction

• Section 23A Crimes Act 1900: Provides a partial defense to murder due to mental health or cognitive impairment.
  • Previously called "substantial impairment by abnormality of mind."
  • Amended by the Mental Health and Cognitive Impairment Forensic Provisions Act 2020.
• No transitional provisions for the applicability to past homicides.
  • Not applicable to cases commenced before the legislation (R v Papanicolaou).
  • Not applicable to homicides committed before the legislation start date (R v Tran).
• Definitions for mental health and cognitive impairment are aligned with the Mental Health and Cognitive Impairment Forensic Provisions Act.

Conditions for Defense

• Section 23A(1): Defense applies only if all other murder charges are resolved against the accused, including self-defense and provocation.
• Section 23A(3): Self-induced intoxication is disregarded in determining liability.
  • Relevant cases include R v Gosling and Zaro v R.
• The impairment must significantly reduce the ability to be convicted of murder, dropping it to manslaughter.
• Opinion evidence on impairment is inadmissible under Section 23A(2).
• The accused carries the burden of proof, and mental illness can be raised by the Crown.
  • Referenced cases: R v Ayoub, R v Jawid.
• Section 151 Criminal Procedure Act 1986: Notice required for raising the defense, specifies evidence stages.

Suggested Written Direction

• Partial Defense in s23A: Limited to mental or cognitive impairment, not both.
• Accused must prove more likely than not:
  1. At the time of the act, capacity to:
     • Understand events,
     • Judge actions,
     • Control self, was substantially impaired.
  2. Impairment must warrant reducing liability for murder to manslaughter.
• Definitions:
  • Mental Health Impairment requires disturbance in thought/mood/volition that is clinically significant.
  • Impairment shouldn't be solely due to substance use.
• Intoxication effects are disregarded.
• If defense fails, verdict is guilty of murder; if successful, guilty of manslaughter.

Suggested Oral Direction

• Substantial Impairment Considerations: Applies if all murder elements are proved by the Crown.
• Defense requires proving substantial impairment at the act time, reducing murder liability.
• Standard of Proof:
  • Accused: Balance of probabilities.
  • Crown: Beyond reasonable doubt.
• Rationale: Recognizes reduced culpability due to impaired mental state.
  • Community standards dictate reduced punishment.
• Substantial Impairment:
  • Accused must prove:
    1. Impairment of understanding/judgment/control.
    2. Impairment's substantial impact on liability.
• Expert evidence (psychiatrist/psychologist) is considered but not binding.

Conclusion

• Self-induced Intoxication: Disregarded in impairment assessment.
• Verdict Summary:
  • Successful defense: Guilty of manslaughter.
  • Unsuccessful defense: Guilty of murder.