Introduction

Aziz v R ([2025] EWCA Crim 605) is a landmark Court of Appeal decision concerning the admissibility and effective challenge of data derived from the EncroChat encrypted communications network. Daniyal Aziz, aged 25 and of previous good character, was tried on multiple counts of conspiracy to supply Class A drugs, conspiracy to supply firearms, possession of prohibited firearms and ammunition, and concealing criminal property. The Crown’s case rested heavily upon expert evidence obtained from intercepted EncroChat messages and “implants” installed on devices under “Operation Venetic.”

Mr Aziz’s defence sought extensive secondary disclosure—raw EncroChat message data for numerous “handles” interacting with his own, “Lushmace”—to enable his expert, Dr Duncan Campbell, to test the reliability and completeness of the prosecution’s schedules. After multiple pre-trial hearings and unresolved objections to disclosure conditions, the trial proceeded without any expert evidence on behalf of Mr Aziz. On appeal, the key issues were:

• Whether the refusal to allow full expert disclosure rendered the trial unfair.
• The correctness of the trial judge’s refusal to adjourn or sever Mr Aziz’s case to secure expert input.
• Procedural fairness in closing speeches and assistance to a litigant in person.
• Whether any breach of fair trial rights under Article 6 ECHR occurred.
• The proper application of sentencing guidelines for large-scale drug and firearms conspiracies.

Summary of the Judgment

The Court of Appeal granted leave to appeal only on two discrete grounds:

1. Ground 2: The overarching contention that Mr Aziz was denied a fair trial because he was left without expert evidence to challenge the reliability of the EncroChat data. This ground was held arguable and leave was granted.
2. Ground 5: The prosecution’s closing speech in respect of Mr Aziz, made without formal permission and containing reference to material not in evidence, which might have been identified and prevented had the proper procedural steps been followed. Leave to argue this ground was also granted.

All other grounds of appeal against conviction—challenging disclosure rulings, adjournment refusals on various dates, the judge’s refusal to allow a change of legal representation, and complaints about assistance to Mr Aziz as a litigant in person—were refused as not arguable.

The application to appeal against sentence, and to extend time for that application, was dismissed as having no real prospect of success. The total custodial sentence of 33 years (24 years for drugs plus 9 years consecutive for firearms) was held to be within the correct guideline range once totality and facts of scale were properly considered.

Analysis

1. Precedents Cited

• R v Stokes and others [2025] EWCA Crim 51 – Provided a factual and technical overview of EncroChat, implant methodology and mutual legal assistance under Operation Venetic.
• R v A, B, D and C [2021] EWCA Crim 128 and R v Atkinson and others [2021] EWCA Crim 1447 – Examined admissibility of EncroChat data, laying down principles of reliability, attribution and chain of custody.
• R v Murray and Baldauf – Established limits on adjournments where a defendant delays trial progress, emphasising the public interest in timely justice.
• C-670/22 MN (2024) – A European Court of Justice ruling on fair trial rights under Directive 2014/41, ultimately held inapplicable post-Brexit but reflecting the principle that evidence must be challengeable to preserve fairness.
• Sentencing authorities: R v Johnson [2022] EWCA Crim 1575, R v Mulvey [2019] EWCA Crim 1835, R v Wright [2017] EWCA Crim 126, R v Sanghera [2016] EWCA Crim 94 – Guided the judge in calibrating the appropriate starting points and ceilings for large-scale drug conspiracies and linked firearms offences.

2. Legal Reasoning

The Court’s reasoning can be broken into two main strands:

• Fair Trial and Expert Disclosure:
  • Article 6 ECHR guarantees a defendant’s right to challenge evidence. Mr Aziz’s expert report raised a plausible attack on the reliability of EncroChat schedules based on discrepancies in message attribution.
  • Multiple pre-trial orders under section 8 Criminal Justice and Immigration Act 1996 required disclosure of raw data packages, but the defence was hampered by contested conditions and funding delays.
  • The Court found the “overarching proposition” arguable: that without expert analysis of all relevant data, Mr Aziz could not effectively challenge the Crown’s digital evidence.
  • Although the trial judge had discretion to balance trial progress against fairness (per Murray and Baldauf), that exercise gave rise to a strong arguable case that Mr Aziz was prejudiced by having no expert evidence at trial.
• Procedural Fairness in Closing Speech:
  • Crown Prosecutors must seek permission under Criminal Procedure Rules 25.9 before making a closing address in respect of a defendant unrepresented at trial or without witnesses called on their behalf.
  • Here, the prosecution spoke to Mr Aziz’s case in closing without formal leave and referred to material (the skeleton argument) not adduced before the jury.
  • The Court granted leave on this procedural ground, recognising that following the proper steps might have averted the error and that, cumulatively with the fairness issue, the point deserved determination.

3. Impact

Aziz v R has significant implications for criminal procedure and the handling of encrypted digital evidence:

• Enhanced Scrutiny of Disclosure Conditions: Courts will be more alert to ensuring that defence experts receive all materials necessary to test reliability, especially in digital-forensics cases.
• Limits on Procedural Delays: While timely trial progression remains important, judges must balance public interest with the defendant’s right to a fair opportunity to challenge technical evidence.
• Criminal Procedure Rule Compliance: Prosecutors must seek leave before addressing an unrepresented defendant’s case in closing; failure may constitute an appealable error.
• Guidance for Litigants in Person: Courts should take care to ascertain what case materials and assistance are needed by a self-represented defendant to avoid unfairness.
• Precedent for Digital Evidence Challenges: Future appellants whose challenges hinge on technical expert analysis will find support for the proposition that denial of adequate expert disclosure raises arguable unfairness.

Complex Concepts Simplified

• EncroChat Network & Implants: EncroChat handsets used encrypted messages. “Implants” were covert software modules remotely installed by French authorities under a European Investigation Order, allowing message interception.
• Secondary Disclosure (s 8 CJIA 1996): A procedural route by which the defence can request material (e.g., raw data) that might undermine the prosecution’s case. The court may order disclosure if it is “reasonably capable” of affecting the verdict.
• Orphan Keys: Cryptographic artifacts arising when messages or metadata cannot be paired between sender and receiver data packages, potentially indicating missing or unreliable records.
• European Investigation Order (EIO): A mutual legal assistance mechanism in the EU for obtaining evidence across borders. Although the UK has left the EU, analogous principles survive under international cooperation agreements.
• Principle of Totality: Sentencing doctrine requiring that consecutive sentences for multiple offences do not produce a cumulative punishment disproportionate to the overall criminality.

Conclusion

Aziz v R underlines the essential balance between the efficient administration of justice and the defendant’s right to a fair trial. Key takeaways include:

• A defendant has an arguable right to full expert disclosure when challenging complex digital evidence, such as EncroChat intercepts.
• Judges must vigilantly ensure that defence experts can access necessary data and that any conditions imposed are workable and justified.
• Prosecutors must comply with Criminal Procedure Rules when addressing a self-represented defendant’s case in closing; failure to obtain permission may be reversed on appeal.
• Even in high-tech prosecutions, fundamental fairness principles under Article 6 ECHR prevail: no trial should proceed in the face of preventable expert-disclosure obstacles.
• Sentencing for large-scale drug and firearms conspiracies remains rigorous but subject to the totality principle to avoid excessive aggregate terms.

The Court of Appeal’s grant of leave on the two crucial grounds emphasizes that procedural missteps—especially those denying effective expert challenge—are not mere technicalities but core to the integrity of criminal justice.