This guide is maintained as a current resource for July 2026 and covers only the laws of England and Wales. Information is for general guidance, not legal advice. Consult a qualified solicitor for advice specific to your situation.
Learn how forensic reports are reconsidered in criminal appeals in England and Wales. This guide explains how appellate courts reassess original expert evidence, the role of fresh forensic evidence and scientific advances, and practical pathways for challenging convictions with new forensic analysis.
Forensic reports often play a vital role in criminal cases. They can include DNA analysis, toxicology results, fingerprint comparisons or medical and scientific expert opinions. At trial, these reports help juries understand complex evidence. But what happens when someone challenges a conviction on appeal and forensic evidence is part of the case? In appeals in England and Wales, the courts must carefully reassess how forensic reports were used, whether they were properly obtained and presented, and in some cases whether new forensic evidence should now be considered. This article explains how forensic reports are treated in criminal appeals, the relevant legal rules, practical steps and common questions.
Understanding Forensic Reports and Expert Evidence
Forensic reports are generally prepared by specialists with scientific or technical expertise. Unlike ordinary factual evidence, forensic reports often include opinion and interpretation of data that lie outside the ordinary experience of judges and jurors. In England and Wales, expert evidence - including forensic reports - is governed by the Criminal Procedure Rules and case law. Expert reports must disclose the expert's qualifications, the data relied on, and the basis for their conclusions.
Forensic evidence ranges widely: from DNA and ballistic tests to pathology reports and digital forensic analysis. At trial, the judge decides on admissibility, ensuring the forensic material can assist the jury without unfair prejudice.
Appeals: The Safety Test
In post‑conviction appeals, the Criminal Division of the Court of Appeal does not re‑try the case. Instead, the fundamental question is whether the conviction is unsafe. Statutory authority for this comes from the Criminal Appeal Act 1968, under which the Court of Appeal must allow an appeal if it thinks the conviction is unsafe.
Forensic reports are reconsidered in this context in two main ways:
- Review of how the original forensic evidence was handled at trial, including admissibility, accuracy and whether defence and prosecution complied with rules of disclosure, and
- Fresh forensic evidence that was unavailable at the time of trial and might affect the safety of the conviction.
Reviewing Original Forensic Reports
Where a conviction is appealed on forensic grounds, the court will examine whether the expert evidence at trial was reliable and properly admitted. Possible issues include:
Errors in Presentation or Interpretation
If forensic reports were incorrectly explained to the jury, misunderstood by counsel, or whether the judge gave inadequate directions about their significance, the appeal court may find the conviction unsafe. Forensic science is specialised, and appellate judges may rely on expert submissions to assess whether the original interpretation remains sound.
Disclosure Failures
Both prosecution and defence have duties to disclose relevant material. If key forensic reports or raw data were withheld, or if material undermining the credibility of the expert was not shared, this can constitute a procedural unfairness. Failure to disclose relevant forensic material can lead to a conclusion that the trial was unfair.
Admissibility and Expert Qualifications
Experts must meet professional standards. The Crown Prosecution Service (CPS) guidance on expert evidence stresses that reports should be robust, logical and transparent. Courts may consider whether experts complied with the Criminal Procedure Rules and appropriate codes of practice in giving their opinion.
If the forensic evidence was inadmissible or unreliable but nonetheless played a significant part in securing conviction, the court may conclude that the conviction is unsafe.
Fresh Forensic Evidence on Appeal
A key feature of criminal appeals in England and Wales is the ability to introduce fresh evidence under section 23 of the Criminal Appeal Act 1968. Fresh evidence means evidence that did not form part of the trial proceedings, was not available earlier, and could affect the outcome of the appeal. The court considers:
- Whether the evidence is credible and capable of belief,
- Whether it may afford grounds for allowing the appeal,
- Whether it would have been admissible at trial, and
- Whether there is a reasonable explanation for why it was not presented at trial.
New forensic reports may arise from advances in scientific methods or retesting of preserved samples. For example, modern DNA technology may produce results that were not possible at the time of trial. In some cases referred by the Criminal Cases Review Commission (CCRC), appeals have succeeded because new forensic analysis showed that original conclusions were fundamentally undermined. In the case of Peter Sullivan, advances in DNA testing led the Court of Appeal to quash his conviction decades after the original trial.
Projects by the CCRC are specifically aimed at identifying cases where new forensic opportunities may impact the safety of older convictions. Such work may involve reviewing cases to see whether developments in science could produce fresh evidence that undermines certainty about identity or guilt.
The Role of the Criminal Cases Review Commission
The CCRC is an independent body that reviews potential miscarriages of justice. It may refer cases to the Court of Appeal where there is a “real possibility” that new evidence or argument - including forensic evidence - could lead to the conviction being overturned. Because the CCRC cannot itself quash convictions, its role is to decide whether a referral to the appeal court is justified. This typically involves detailed examination of forensic material and consideration of advances in science since the original trial.
The CCRC's work has attracted scrutiny over its forensic expertise, with commentators arguing the Commission should make greater use of independent scientific specialists in assessing complicated forensic issues.
Practical Steps for Appeals Involving Forensic Reports
Legal Representation
Challenging a conviction on forensic grounds is technically complex. Appellants should have specialist appellate representation to assess whether procedural errors, disclosure failures or new forensic evidence provide a sustainable ground for appeal.
Gathering Expert Evidence
If a fresh forensic report is to be relied on, it must be supported by credible scientific evidence. Counsel will usually engage independent experts to test and interpret forensic material and prepare reports that meet court standards for admissibility.
Documentation and Explanation
Successful admissions of fresh forensic evidence require a clear explanation of why it was not available at trial. This may involve affidavits from experts or detailed statements regarding the scientific advances that underpin new results.
Time Limits and the CCRC Pathway
Appeals directly to the Court of Appeal have tight time limits. If these have passed, applications to the CCRC for review may be the appropriate route before a fresh appeal can be lodged.
Challenges and Considerations
- Scientific Complexity: Forensic science evolves, and courts must balance respecting past expert opinion with the possibility that new techniques cast doubt on earlier conclusions.
- Resource Inequality: Defence teams often have fewer resources to commission expert analysis than prosecution bodies, potentially limiting the ability to challenge forensic reports effectively.
- Judicial Discretion: Even where fresh forensic evidence is credible and admissible, the appeal court retains discretion on its impact on the safety of the conviction.
Key Takeaways
Forensic reports are key pieces of evidence that must withstand rigorous re‑examination on appeal. Appellate courts in England and Wales assess whether original forensic evidence was reliable, whether it was properly disclosed and admissible, and whether new forensic material justifies allowing an appeal. Fresh forensic evidence, particularly where scientific advances have occurred, can be persuasive in demonstrating that a conviction is unsafe. The CCRC plays an important intermediary role in identifying cases where new forensic opportunities may change established outcomes.
