R v BNA: Rationality and Abuse of Process in Modern Slavery Victims’ Prosecutions under CPS Guidance

Introduction

In R v BNA [2025] EWCA Crim 496 the Court of Appeal (Criminal Division) considered whether the prosecution of a person subsequently recognised as a victim of modern slavery constituted an abuse of process, and whether a late plea-time extension and fresh evidence ought to be admitted. The applicant, a 44-year-old Brazilian national, had pleaded guilty to possession of an imitation firearm with intent to cause fear of violence under section 16A of the Firearms Act 1968. After conviction and sentence, he was referred into the National Referral Mechanism (“NRM”) and in June 2021 the Single Competent Authority (“SCA”) made a conclusive grounds finding that he had been trafficked and forced into labour. The applicant sought: (1) an anonymity order, (2) an extension of time to appeal his conviction, and (3) leave to adduce fresh evidence on the modern‐slavery circumstances underpinning his plea.

Summary of the Judgment

The Court granted the anonymity order under section 11 of the Contempt of Court Act 1981, acknowledging the risk of re-trafficking and the open-justice principle. It then considered the extension-of-time application and fresh evidence. Although it was clear that, from 9 May 2018 onwards, the Crown Prosecution Service (“CPS”) had failed to follow its four-stage guidance for victims of trafficking or slavery, the Court nonetheless reviewed the decision to prosecute on traditional rationality and public-interest grounds. It concluded, after an extensive credibility analysis, that the applicant’s modern-slavery account was “manifestly implausible” and that even had the CPS investigated in 2018, it would have rationally concluded that he was not a genuine victim. His conviction was therefore not an abuse of process and his plea was safe. The application for an extension of time was refused.

Analysis

Precedents Cited

• R v AAD [2022] EWCA Crim 106 – Emphasises deference to CPS prosecutorial decisions and limits court intervention absent a “clearly flawed” process.
• R v LM [2011] 1 Cr App R 12 – Abuse-of-process principles where CPS guidance on victims of trafficking is properly applied.
• AFU [2023] EWCA Crim 23 – Summarises the approach to abuse-of-process claims by alleged victims of trafficking, highlighting the four-stage CPS guidance and the court’s rationality review.
• AH [2023] EWCA Crim 808 – Confirms that failure to follow CPS guidance is relevant but not decisive; decisions to prosecute are reviewed for rationality and procedural fairness.
• R v S(G) [2018] EWCA Crim 1824 – Formulates the public-interest test in trafficking cases: whether the “dominant force of compulsion” reduces criminality below the public-interest threshold.
• Brecani [2021] EWCA Crim 731 – Admissibility of post-conviction conclusive grounds decisions on appeal and their usual respect unless manifestly flawed.
• R v Johnson [2023] EWCA Crim 1609 – Interpretation of statutory schedules; here relied on by analogy to show that section 45 Modern Slavery Act 2015 does not cover offences in Schedule 4.

Legal Reasoning

The Court’s reasoning unfolded in three main strands:

1. CPS Four-Stage Guidance
   The applicable 2018 CPS guidance required prosecutors to:
   
   • Stage 1: Identify whether there is reason to believe the suspect may be a victim of trafficking or slavery;
   • Stage 2: Assess if a common-law duress defence is clearly available;
   • Stage 3: Assess if a statutory defence under section 45 Modern Slavery Act 2015 applies;
   • Stage 4: If no defences apply, determine whether it is in the public interest to prosecute, weighing offence seriousness against compulsion.
   The Judgment found no sign of victim identification until the applicant’s Defence Statement was filed on 9 May 2018; thereafter the CPS failed to comply with the guidance.
2. Rationality and Abuse of Process
   Even where CPS guidance has not been followed, the court’s intervention is justified only if the decision to prosecute lacks rationality or procedural fairness (AFU; AH). The appellate court must not substitute its judgment simply because it disagrees with the decision to prosecute (AAD). Instead it reviews whether, on the evidence known then or in a fair retrospective assessment, it was rational to proceed.
3. Credibility, SCA Decision and Public Interest
   Although conclusive grounds decisions of the SCA attract respect, they are not binding on a criminal court if the victim’s account is demonstrably implausible (AAD; Brecani). The Court conducted a detailed comparison of the applicant’s varying accounts (police interview, defence statements, asylum statements, psychiatric reports, McCook material) and concluded his modern-slavery narrative was inconsistent with forensic evidence, contemporaneous documents, and inherent probabilities. In those circumstances the Court was satisfied that even had the CPS investigated in 2018, it would have rationally concluded that the applicant was not a genuine victim and the public interest in prosecuting a firearms offence remained paramount.

Impact

R v BNA clarifies several important points:

• Non-compliance with CPS guidance on victims of modern slavery is a serious procedural flaw, but does not automatically invalidate a prosecution if the decision to prosecute is otherwise rational and fair.
• Conclusive grounds decisions by the SCA, while entitled to respect, may be disapplied on appeal where the appellant’s narrative is manifestly implausible.
• The public-interest test in trafficking cases (R v S(G)) remains the decisive inquiry: was the compulsion so overwhelming that criminality fell below the public-interest threshold?
• Section 45 Modern Slavery Act 2015 does not extend to offences listed in Schedule 4, including section 16A Firearms Act 1968—whether with a real or imitation weapon.
• The appellate court will conduct a comprehensive credibility analysis, comparing all contemporaneous and later accounts, forensic and documentary evidence, and expert psychiatric reports.

Complex Concepts Simplified

• Abuse of Process: A claim that a trial or prosecution was so unfair or flawed that it should be set aside.
• CPS Four-Stage Guidance: The Crown Prosecution Service’s step-by-step test for handling suspects who might be victims of trafficking or modern slavery.
• Conclusive Grounds Decision: A binding administrative finding by the SCA that an individual is a victim of modern slavery “on the balance of probabilities.”
• Manifestly Implausible: So unlikely or self-contradictory that no reasonable tribunal could accept it.
• Rationality Review: The appellate court’s deferred scrutiny of a prosecutorial decision to ensure it was neither arbitrary nor unfair.
• Section 45 Defence: A statutory defence in the Modern Slavery Act 2015, unavailable for offences listed in Schedule 4 (e.g. firearm-related offences under section 16A).

Conclusion

R v BNA sets a balanced precedent on the interplay between modern-slavery recognition, CPS procedural obligations, and prosecutorial rationality. While emphasising the importance of early identification and strict adherence to guidance for victims of trafficking, the Court confirmed that failures in that respect do not automatically warrant quashing convictions. Instead, where an appellant’s trafficking narrative is demonstrated to be manifestly implausible, the court will steadfastly uphold the public-interest in prosecuting serious offences. This decision will guide practitioners in both prosecution and defence of modern-slavery cases, ensuring that procedural fairness, credibility assessment, and public-interest considerations remain at the forefront of appellate review.