Introduction

The case of Weir MacKay against Her Majesty's Advocate ([2020] HCJAC 24) presents a pivotal examination of the principles surrounding causation in homicide charges within Scottish law. The appellant, Weir MacKay, was initially convicted of culpable homicide and appealed both the conviction and the 14-year imprisonment sentence. This commentary delves into the intricacies of the case, analyzing the court's interpretation of causation, the application of legal precedents, and the broader implications for future criminal jurisprudence.

Summary of the Judgment

On June 24, 2020, the Scottish High Court of Justiciary delivered its judgment in the appeal brought by Weir MacKay against Her Majesty's Advocate. MacKay and his co-accused, Allan Doherty, were charged with murder following the death of Karen Young, who suffered multiple injuries leading to her demise. MacKay was convicted of culpable homicide, a lesser charge than murder, due to the jury's determination that his actions did not make a substantial contribution to Young's death as required by Scottish law.

The core contention of the appeal was that the jury's verdict contradicted the directions given by the trial judge, particularly regarding the necessity of establishing that the accused's conduct made a substantial contribution to the victim's death. The High Court scrutinized the evidence, especially the post-mortem findings and expert testimonies, ultimately agreeing with the appellant. The court quashed the culpable homicide conviction and substituted it with a conviction for assault, emphasizing that the prosecution failed to prove beyond reasonable doubt that MacKay's actions significantly contributed to Young's death.

Analysis

Precedents Cited

The judgment extensively referenced key precedents that shaped the legal understanding of causation in homicide cases:

• Johnston v HM Advocate 2009 JC 227: Established that for a homicide charge, it is sufficient that the accused's actions made a significant contribution to the death, even if other factors were also involved.
• Cheshire [1991] 1 WLR 844: Defined a material contribution as one which is more than negligible, reinforcing the threshold required for establishing causation.
• McDade v HM Advocate [2012] HCJAC 38: Clarified that even if the assault alone might not cause death, it could still lead to a fatal outcome through mechanisms like cardiac arrhythmia, provided the prosecution establishes a substantial link.

These precedents collectively underscore the necessity for the prosecution to demonstrate a clear and substantial link between the accused's actions and the victim's death, beyond mere association or simultaneous factors.

Legal Reasoning

The court's legal reasoning focused primarily on the concept of causation and the requirement that the accused's conduct must have made a substantial contribution to the victim's death. The High Court noted that while Dr. Turner's expert testimony suggested a potential mechanism (cardiac arrhythmia induced by stress) through which the appellant's assault could have contributed to the death, this remained a theoretical possibility rather than an established fact.

The court emphasized that causation must be supported by evidence that moves beyond hypothesis to demonstrate that the accused's actions were a working and significant cause of death. In this case, the more direct cause—compression of the neck leading to asphyxiation—was clearly linked to Doherty's actions, whereas the appellant's infliction of blunt force injuries did not meet the threshold of substantial contribution required for culpable homicide.

Furthermore, the jury's removal of the appellant's involvement in specific violent acts from the charge diminished the evidence needed to establish his substantial contribution to death. The court agreed that without concrete evidence of a cardiac arrhythmia caused by the appellant's assault, the conviction for culpable homicide was untenable.

Impact

This judgment has significant implications for future homicide cases in Scotland:

• Clarification on Causation: Reinforces the necessity for clear and substantial evidence linking the accused's actions to the victim's death, discouraging convictions based on speculative or indirect contributions.
• Jury Directions: Highlights the importance of precise jury instructions regarding causation and the burden of proof required to establish a substantial contribution to death.
• Expert Testimony Scrutiny: Emphasizes that expert opinions must translate into concrete evidence of causation beyond theoretical mechanisms to influence verdicts.

Additionally, the decision demonstrates judicial willingness to rectify miscarriages of justice where convictions are not firmly grounded in the evidence, thereby upholding the integrity of the judicial process.

Complex Concepts Simplified

Conclusion

The High Court's decision in Weir MacKay v. HM Advocate [2020] HCJAC 24 serves as a critical reaffirmation of the principles governing causation in homicide charges under Scottish law. By meticulously evaluating the evidence and upholding the necessity for a substantial contribution to death, the court emphasized the importance of robust and concrete links between an accused's actions and the resulting fatality.

This judgment not only rectifies an individual conviction based on insufficient causative evidence but also sets a precedent that underscores the judiciary's commitment to fairness and the rigorous application of legal standards. Future cases will undoubtedly reference this decision to ensure that convictions for culpable homicide and similar charges are predicated on unequivocal evidence of substantial contribution, thereby safeguarding against unjust outcomes.