Expert Witness Journal Issue 63 October 2025 - Flipbook - Page 95
Digital Evidence in the Dock:
Admissibility, Reliability and Forensic
Practice for Lawyers and the Public
This paper provides a practical guide to how digital evidence is identi昀椀ed, captured, analysed
and presented in criminal and civil proceedings in England and Wales, with comparative
nods to international technical standards. It explains the legal and scienti昀椀c foundations that
underpin admissibility and weight—covering the Forensic Science Regulator’s statutory Code
of Practice (the ‘FSR Code’), the Criminal Procedure Rules and Criminal Practice Directions
on expert evidence, the Criminal Procedure and Investigations Act (CPIA) disclosure regime,
and good-practice standards such as ISO/IEC 27037 and BS 10008.
The paper is written for a general audience with an
interest in justice, but assumes the reader has a basic
legal grounding. It sets out the end‑to‑end digital
forensics lifecycle, common pitfalls (from weak chain of
custody to tool validation gaps), options to remediate
non‑compliance, and a roadmap for practitioners who
must work across the legal–technical boundary.
Disclosure duties are set by the CPIA 1996 (and Code
of Practice) and the Attorney General’s Guidelines on
Disclosure (most recently updated to May 2024), with
speci昀椀c guidance for the digital context.
Technical and management standards. ISO/IEC
27037
provides
foundational
guidance
on
identi昀椀cation, collection, acquisition and preservation
of digital evidence; BS 10008:2020 addresses evidential
weight and legal admissibility of electronically stored
information by specifying controls that demonstrate
authenticity and integrity; NIST Special Publications
(e.g., SP 800‑101r1 for mobile device forensics) and
testing programs help practitioners understand
method limitations and validation requirements.
1. Introduction
Digital traces now feature in almost every investigation:
mobile phone content, cloud backups, messages,
location histories, CCTV, vehicle telemetry, and data
captured by internet platforms. For courts, the promise
is better fact‑昀椀nding; the risk is unreliable science or
unfair intrusion into privacy. For lawyers, the challenge
is to interrogate methods, not only conclusions. For the
public, trust hinges on clear standards, transparency
about uncertainty, and rigorous disclosure.
Three questions structure this guide:
(1) When is digital evidence admissible?
(2) What makes it reliable?
(3) How should professionals collect, analyse and
disclose it so that courts - and the public - can
have
con昀椀dence in the outcome?
We highlight the post‑2023 statutory footing for the
Forensic Science Regulator, the refreshed Criminal
Practice Directions 2023, the Attorney General’s 2024
Disclosure Guidelines, and established international
standards that shape day‑to‑day practice.
3. Background and Current State
Police and private practitioners operate in a hybrid
landscape of statutory requirements and professional
practice. The College of Policing’s Authorised
Professional Practice (APP) on extracting material
from digital devices seeks consistent, lawful and
proportionate seizure and extraction, complemented
by the Home O昀케ce code under the Police, Crime,
Sentencing and Courts Act 2022 on voluntary device
access. Operationally, forces are moving towards
greater accreditation and standardisation, while
grappling with data volumes, encryption, and
cloud‑sourced evidence.
Against that backdrop, four themes recur in court:
chain of custody and continuity; validation and
competence; scope and proportionality (especially
for victims’ and witnesses’ devices); and disclosure
management for vast datasets.
2. Legal, Regulatory and Standards Landscape
Key legal instruments (England & Wales). The Forensic
Science Regulator Act 2021 establishes the Regulator
in statute and requires a Code of Practice. A statutory
FSR Code came into force in October 2023; compliance
is increasingly expected across policing and providers,
with UKAS managing accreditation to ISO standards
for laboratory and scene activities. Criminal courts
govern expert evidence primarily through the Criminal
Procedure Rules (CrimPR) Part 19 and the Criminal
Practice Directions (CPD) 2023 (as amended), which set
duties of independence, report content, declarations
of compliance, and case‑management expectations.
EXPERT WITNESS JOURNAL
4. Methodology and Lifecycle
This guide synthesises statute, procedural rules,
regulator guidance and international standards,
alongside practical experience from digital forensics.
We, at Computer Forensics Lab adopt the lifecycle
model ‑ identify, preserve, acquire, examine, analyse,
report, present, and archive ‑ mapping each stage to
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