Forensic Deconstruction: Leveraging Inconsistencies in Police and Witness Evidence Under the Evidence Act 1995

Introduction

In criminal proceedings, the prosecution's case is often a construct of layered narratives drawn from police officers and civilian witnesses. The Evidence Act 1995 (Cth/NSW) provides the statutory architecture governing the admissibility and weight of this evidence. For the defence advocate, a meticulous, technical dissection of inconsistencies within and between these evidence streams is not merely a tactical exercise but a fundamental methodological approach to creating reasonable doubt. This post outlines a forensic framework for deconstructing prosecution evidence by leveraging inconsistencies, grounded in the Act's provisions and appellate authority.

The Statutory Foundation: Credibility, Reliability, and the Discretion to Exclude

Section 55 of the Evidence Act defines 'relevant evidence' as that which could rationally affect the assessment of the probability of a fact in issue. The credibility of a witness is expressly a fact in issue (s 101A). Inconsistencies go directly to credibility and reliability. Section 102 establishes that credibility evidence is not admissible unless a specific exception applies. However, prior inconsistent statements of a witness (including police) are admissible under s 43 to prove credibility, subject to the procedural fairness requirements of putting the statement. Critically, s 137 mandates that the court must refuse to admit prosecution evidence if its probative value is outweighed by the danger of unfair prejudice to the defendant. A demonstrable pattern of significant inconsistencies can form the basis for a s 137 application, arguing the evidence's low probative value given its unreliability, versus the high prejudicial value of a jury hearing a seemingly coherent but flawed account. The High Court in IMM v The Queen (2016) 257 CLR 300 reaffirmed the centrality of reliability to the probative value calculus.

Categorising and Attacking Inconsistencies: A Typology

A systematic approach requires categorising inconsistencies to target them with appropriate legal and rhetorical force.

1. Internal Inconsistencies (Prior Inconsistent Statements): These occur when a witness's testimony contradicts their own prior statement (e.g., police notebook, ERISP, signed witness statement). Procedure under s 43 is key. The foundational case of R v Souleyman [1996] 40 NSWLR 712 outlines the judicial discretion to allow cross-examination on the statement without it being shown to the witness first, a potent tool for confronting evasive police witnesses.
2. External Inconsistencies (Contradictions Between Witnesses): Where accounts of two or more prosecution witnesses conflict on a material particular (e.g., sequence of events, descriptions, utterances). This undermines the prosecution's singular narrative. Reference to R v RPS (unreported, NSWCCA, 13 August 1997) is apt, where significant discrepancies between police officers' accounts of an arrest led to a reasonable doubt direction.
3. Inconsistencies with Objective Evidence: Discrepancies between a witness's account and incontrovertible objective evidence (CCTV, forensic timelines, audio recordings, telemetry data). These are the most powerful. The NSWCCA in R v Bilal [2003] NSWCCA 444 emphasised that where a witness account is irreconcilable with objective facts, it can render the entirety of their evidence unreliable.
4. Inconsistencies Owing to Police Methodology: Flaws in police processes that generate inconsistency (e.g., breach of the Code of Practice for CRIME (Custody, Rights, Investigation, Management and Evidence), failure to contemporaneously note, collusion or 'cuing' between officers). This elevates the attack from the individual witness to the integrity of the investigation, potentially engaging the Bunning v Cross (1978) 141 CLR 54 discretion for exclusion of evidence unfairly or improperly obtained.

The Forensic Methodology: From Discovery to Closing Address

Effective deployment is methodical, not serendipitous.

1. Discovery Phase: Secure all primary materials: police notebooks (via subpoena), original witness statements, COPS entries, ERISP tapes and transcripts, duty logs. Chronologise all events from multiple sources.
2. Analytical Phase: Create a detailed matrix or concordance. Map each witness's account (by time and source) against every other account and objective evidence. Flag material (goes to an element of the offence) versus immaterial inconsistencies. Identify 'clusters' of inconsistency around key events.
3. Strategic Phase: Decide the primary theory: Is the inconsistency indicative of innocent mistake, reconstruction, or deliberate untruthfulness? The chosen theory must align with the overall defence case. Plan the sequence of cross-examination to expose and crystallise the inconsistency for the tribunal of fact, using the procedural tools in ss 42-43 of the Evidence Act.
4. Deployment Phase: In cross-examination, first commit the witness to their current version in-chief. Then, with precision, confront with the prior inconsistent statement, complying with the rule in Browne v Dunn (1893) 6 R 67. For police witnesses, explore training, procedures, and reasons for note-taking delays to undermine the reliability of their recorded recollection.

Practical Checklist for Defence Practitioners

• [ ] Exhaust Disclosure: Subpoena all preliminary notes, draft statements, and police duty logs.
• [ ] Chronologise & Map: Build a master timeline and evidence matrix.
• [ ] Categorise Inconsistencies: Label each as internal, external, or objective. Assess materiality.
• [ ] Evidence Act Compliance: Note relevant sections (ss 43, 102, 137, 138) for each major inconsistency.
• [ ] Formulate s 137/138 Applications: Draft pre-trial motions to exclude evidence where inconsistencies critically undermine probative value.
• [ ] Plan Cross-Examination Sequence: Structure questioning to maximise the impact of the revealed inconsistency.
• [ ] Prepare Jury Directions: Draft requested directions on unreliable witness evidence (R v Stewart [2001] NSWCCA 260) and the need for cautious assessment where inconsistencies are proven.

Conclusion

Inconsistencies are the fractures in the prosecution's edifice. A defence grounded in the forensic deconstruction of these fractures is a rigorous application of the Evidence Act 1995. It shifts the discourse from a mere 'word against word' contest to a demonstration that the prosecution's own evidence fails to meet the requisite standard of proof beyond reasonable doubt, due to intrinsic unreliability. By methodically cataloguing inconsistencies, categorising them legally, and deploying them through the Act's mechanisms, counsel performs the essential function of testing the case to destruction, upholding the paramount principle that a conviction must be based on reliable, probative evidence.