The judgment references several pivotal cases that have shaped the handling of fresh evidence and the admissibility of novel scientific techniques in criminal appeals:

• R v Bain [2004] 1 NZLR 638 (CA): Established the threefold test for admitting fresh evidence on appeal, focusing on freshness, credibility, and the potential to influence the verdict.
• R v Matenga [2009] 3 NZLR 145: Affirmed the approach that the appellate court must independently assess whether new evidence could reasonably lead to a different verdict.
• R v Pendleton [2002] 1 WLR 72: Emphasized that appellate courts should assess whether fresh evidence might reasonably have affected the jury's decision to convict.
• Daubert v Merrell Dow Pharmaceuticals Inc 509 U.S. 579 (1993): Provided factors for evaluating the reliability of scientific evidence, later adapted in New Zealand jurisprudence.
• Blake v Cell Tech International Inc (2009) 228 Ore App 388: Highlighted the necessity of empirical testing and peer review for the admissibility of novel scientific evidence.

Jurisdiction and Admittance of Fresh Evidence

The Privy Council affirmed its jurisdiction to hear Lundy's appeal despite the abolition of appeals to the Privy Council from New Zealand criminal cases post-2003. It determined that Lundy's application met the criteria for fresh evidence due to the introduction of new expert testimonies that were not available during the original trial and that could plausibly affect the verdict.

Reliability and Admissibility of Immunohistochemistry (IHC)

A central issue was the reliability of IHC in identifying CNS tissue on Lundy's shirt. The original trial relied heavily on forensic evidence indicating that CNS tissue from Lundy's wife was present on his clothing, bolstering the prosecution's case. However, new expert evidence challenged the validity of these findings:

• Professor Philip Sheard: Criticized the experimental rigor of Dr. Miller's IHC techniques, questioning antibody specificity and the preservation state of the tissue samples.
• Professor Helen Whitwell: Asserted the impossibility of definitively identifying the tissue's origin based solely on Dr. Miller's slides.
• Professor Kevin Gatter: Confirmed the flaws in Dr. Miller's methodology, advocating for cautious interpretation of IHC in forensic contexts.
• Professor Michael Gown: Supported the critiques of IHC reliability, emphasizing the necessity for corroborative scientific evidence.

Conversely, Dr. Miller and other prosecution experts staunchly defended the IHC evidence, attempting to discredit the new critiques as lacking practical forensic context.

Impact on Safety of Conviction

The Privy Council assessed whether the fresh evidence introduced could have influenced the jury's verdict. Given the profound doubts cast on the key forensic evidence due to the unreliable IHC methodology, the court concluded that there was a real risk of an unsafe conviction, warranting the quashing of Lundy's convictions.

This judgment has significant implications for future criminal cases, particularly concerning the admissibility of novel scientific evidence:

• Enhanced Scrutiny of Forensic Techniques: Courts are now more vigilant in assessing the scientific validity and acceptance of forensic methods used as pivotal evidence in criminal trials.
• Encouragement of Comprehensive Expert Review: The case underscores the necessity for thorough and independent expert evaluations, especially when novel techniques are employed.
• Facilitation of Fair Retrials: By admitting credible fresh evidence that challenges foundational aspects of the prosecution's case, the judgment reinforces the principle that convictions should be safe and just.
• Guidance for Defense Strategies: Defense counsel may be more proactive in seeking and presenting fresh scientific evidence post-trial to contest questionable convictions.

Immunohistochemistry (IHC)

IHC is a laboratory technique used to visualize specific proteins or antigens in tissue sections using antibodies tagged with fluorescent or chromogenic labels. In forensic science, IHC can help identify the type of tissue found at a crime scene, such as CNS tissue, by targeting brain-specific proteins.

Fresh Evidence

Fresh evidence refers to new information introduced during an appeal that was not available during the original trial. For it to be admissible, it must be credible, fresh (not obtainable with reasonable diligence before the trial), and significant enough to potentially alter the trial's outcome.

Miscarriage of Justice

This term denotes a situation where a legal error or new evidence results in an unfair conviction or acquittal. The appellate court must assess whether the new evidence presents a real risk that the original verdict may be unsafe or unjust.