1. Introduction: The Judicial Function in Evidence Assessment
The assessment of evidence constitutes the core of the judicial function in civil proceedings. Unlike questions of law, which are amenable to precise rules and principles, the evaluation of evidence is an inherently discretionary exercise informed by legal principle, experience, and reasoned judgment. The ultimate question is whether the tribunal of fact has been persuaded to the requisite standard that the facts necessary to establish the cause of action or defense have been proved.
The standard of proof in civil proceedings is the balance of probabilities.
1.1 The Briginshaw Principle: Subtleties and Application
While the balance of probabilities remains the applicable standard, the High Court in Briginshaw recognized that the degree of satisfaction required may vary according to the gravity of the matters alleged. Dixon J articulated this principle (at 361-362):
"The seriousness of an allegation made, the inherent unlikelihood of an occurrence of a given description, or the gravity of the consequences flowing from a particular finding, are considerations which must affect the answer to the question whether the issue has been proved to the reasonable satisfaction of the tribunal."
It is crucial to understand that Briginshaw does not alter the standard of proof or create a "third standard" between the civil and criminal standards. Rather, it recognizes that the more serious the allegation, the more carefully the court should scrutinize the evidence before being satisfied on the balance of probabilities (Neat Holdings Pty Ltd v Karajan Holdings Pty Ltd (1992) 110 ALR 449 at 449-450).
This principle operates as a practical recognition that, in considering whether the balance of probabilities has been met, the nature and consequences of the facts to be proved are inherently relevant to whether the court feels an actual persuasion that they occurred. This nuance was further clarified in Cubillo v Commonwealth of Australia (No 2) (2000) 103 FCR 1 at [322], where the Court emphasized that the Briginshaw principle does not impose a higher standard of proof but "merely reflects a conventional perception that members of society do not ordinarily engage in fraudulent or criminal behavior."
2. Assessing Oral Evidence
2.1 Credibility versus Reliability
A critical distinction when evaluating oral testimony is that between credibility (honesty) and reliability (accuracy). A witness may be entirely truthful yet provide unreliable evidence due to perception, memory, or articulation issues. Conversely, a witness might generally be unreliable but accurately recall certain specific details.
In Doherty v Sampey [2023] WASC 10, Allanson J demonstrated this distinction in practice, finding that some witnesses, while attempting to be honest, had memories affected by "the passage of time... strong emotions... and, in the case of Norris, his health" (at [31]). The court proceeded to accept parts of testimony while rejecting others, showing the nuanced approach required.
2.2 Demeanor: A Cautionary Approach
Traditional emphasis on demeanor as a central element in credibility assessment has been significantly qualified by modern jurisprudence, which recognizes the limitations of demeanor-based evaluations. This shift is evident in Fox v Percy (2003) 214 CLR 118, where the High Court noted at [30]-[31] that "recent research has cast doubt on the ability of judges (or anyone else) to tell truth from falsehood accurately on the basis of demeanor."
The Full Court of the Federal Court articulated this limitation in SBAS v Minister for Immigration and Multicultural and Indigenous Affairs [2003] FCAFC 195 at [82], observing that "it is all too easy for a judge to think that a shifty-looking witness is a liar, when his appearance may be due to stress, embarrassment... [or] personality." This recognition requires judges to treat demeanor as just one factor among many, with greater emphasis placed on objective factors such as consistency with established facts, contemporaneous documentation, and inherent probability.
2.3 Consistency and Corroboration
Consistency takes multiple forms that must be evaluated differently:
2.3.1 Internal Consistency
Minor inconsistencies within a witness's testimony may actually enhance credibility, as they can indicate lack of rehearsal or fabrication. Conversely, perfect consistency on peripheral details over multiple tellings may suggest preparation rather than genuine recall. The focus should be on whether inconsistencies relate to central or peripheral matters, and whether they follow a pattern suggesting unreliability or merely reflect natural memory processes.
2.3.2 External Consistency
External consistency involves the relationship between a witness's testimony and:
Objectively established facts
Contemporaneous documents
The testimony of other witnesses, particularly independent ones
Previous statements by the same witness
When assessing external consistency, particular weight should be given to consistency with contemporaneous documents and objectively verifiable facts. The Court of Appeal in Kakavas v Crown Melbourne Ltd [2012] VSCA 95 at [449] observed that "the objective facts... provided the most reliable yardstick against which to measure the reliability of the evidence given by the various witnesses about past events."
2.4 Memory and Recollection
Courts must be acutely aware of the reconstructive nature of memory, particularly regarding conversations or events occurring years before trial. The inherent frailties of human memory were articulated by McLelland CJ in Eq in Watson v Foxman (1995) 49 NSWLR 315 at 319:
"Human memory of what was said in a conversation is fallible for a variety of reasons, and ordinarily the degree of fallibility increases with the passage of time... The difficulty is compounded when the conversation is heard differently by different listeners, and is affected by the bias and interest of those who purport to recall it."
This scientific understanding of memory has important consequences for evidence assessment:
Greater weight will typically be accorded to contemporaneous documents than to later recollections
The more time that has elapsed, the more carefully oral recollections should be scrutinized
Memories of specific conversations should be assessed with particular caution
The court should consider the effect of post-event discussions or information that may have influenced memory
Nevertheless, as Vaughan J noted in Westgyp Pty Ltd v Northline Ceilings Pty Ltd [2018] WASC 244 at [53], and as endorsed by Allanson J in Doherty v Sampey [2023] WASC 10 at [35], the correct approach is not to "simply place little reliance on oral recollection" but to "assess that evidence in light of its inherent probabilities in the context of the objectively established facts."
2.5 Reconstruction versus Independent Recollection
Courts should be alert to the distinction between genuine independent recollection and reconstructed memory. A witness who is reconstructing what "must have happened" based on knowledge of events, documents reviewed, or subsequent conversations, is not providing direct evidence of recollection. While reconstruction may still be valuable evidence, it does not carry the same weight as authentic independent recollection.
In Onassis v Vergottis [1968] 2 Lloyd's Rep 403 at 431, Lord Pearce observed that "witnesses, especially those who are emotional, who think that they are morally in the right, tend very easily and unconsciously to conjure up a legal right that did not exist. It is a truism, often used in accident cases, that with every day that passes the memory becomes fainter and the imagination becomes more active."
2.6 Interest and Bias
A witness's interest in the outcome of proceedings, whether financial, emotional, or reputational, requires the court to scrutinize their evidence with particular care. This does not mean that interested witnesses should be disbelieved merely because of their interest; rather, their evidence should be tested against objective facts and inherent probabilities with heightened attention.
Allanson J's treatment of the evidence of Mr. Hughes in Doherty v Sampey [2023] WASC 10 illustrates this approach. The court observed that Mr. Hughes, as a loyal friend to one party, could not be regarded "in the same way as... a truly independent witness" because he was "obviously affected by his friend's distress" (at [97]). The court acknowledged that this relationship may have "distorted his recollection of events" without automatically rejecting his evidence.
2.7 Witness Unavailability: Special Considerations
When evidence relates to dealings with a person who cannot give evidence (due to death, incapacity, or non-attendance), particular caution is required. This principle has been articulated in cases such as Blacket v Barnett [2017] NSWSC 1032 at [243]-[250], where the court emphasized the need for careful scrutiny of evidence about conversations with deceased persons.
These principles were applied by analogy in Ng v Sevastos [2024] WADC 75, where Curwood DCJ carefully scrutinized evidence concerning dealings with a party who could not testify due to cognitive impairment. The court accepted the plaintiff's evidence only after finding it corroborated by contemporaneous documents and conduct.
The rationale for this heightened scrutiny is that the evidence cannot be tested through cross-examination of the other participant in the conversation or transaction, removing a crucial safeguard for testing reliability and truthfulness.
2.8 Partial Acceptance of Evidence
The principle that a court may accept some parts of a witness's evidence while rejecting others is well-established. In Cubillo v Commonwealth of Australia (No 2) (2000) 103 FCR 1 at [118], the court noted that "the trial judge is entitled to believe part of the evidence given by a witness and to reject the rest" after making an assessment of all the evidence.
This selective approach recognizes that witnesses may be honest and accurate on some matters but not others, whether due to memory lapses, unconscious bias, or deliberate deception on specific points. The court's task is to identify which aspects of testimony are reliable and which are not, based on objective indicia of reliability rather than making a global assessment of the witness's credibility.
3. Assessing Documentary Evidence
3.1 Categories and Weight
Different categories of documentary evidence attract different evaluative approaches:
3.1.1 Contemporaneous Business Records
Documents created in the ordinary course of business, without contemplation of litigation, generally have enhanced probative value. This includes invoices, ledgers, meeting minutes, emails, and routine reports. Such documents are typically created for operational rather than forensic purposes and are less likely to reflect bias or advocate a particular position.
3.1.2 Self-Serving Documents
Documents created by a party after a dispute has arisen, or in contemplation of potential litigation, warrant greater scrutiny. While not automatically discounted, such documents may reflect a party's desired interpretation of events rather than an objective record.
3.1.3 Official Records and Public Documents
Documents created pursuant to statutory or regulatory obligations often carry heightened reliability due to the formal responsibilities under which they were prepared.
3.2 Authentication and Chain of Custody
Before a document's content can be evaluated, its authenticity must be established. This involves consideration of:
Who created the document and when
How the document has been stored and preserved
Whether there is evidence of alteration or tampering
The source from which the document was obtained
In Ng v Sevastos [2024] WADC 75, questions arose about an envelope allegedly signed by a key witness but kept in the defendant's safe. The court carefully considered the chain of custody and potential for alteration when assessing its evidentiary value.
3.3 Electronic Documents: Special Considerations
Electronic documents present unique challenges and considerations:
Metadata may provide important information about creation, modification, and access
Electronic documents may exist in multiple versions
Questions of authentication are often more complex
The manner of production and preservation may affect reliability
Courts should be alert to these issues when assessing electronic evidence, particularly when authenticity or integrity is contested.
3.4 Interpreting Documentary Evidence
The interpretation of documents involves both their literal content and contextual meaning. Courts should consider:
The purpose for which the document was created
The author's knowledge and authority
The intended audience
Contemporary circumstances that inform meaning
Technical or specialized terminology
Consistency with related documents
In commercial contexts, the objective approach to contractual interpretation articulated in Electricity Generation Corporation v Woodside Energy Ltd (2014) 251 CLR 640 at [35] may be instructive – focusing on what a reasonable business person would understand the document to mean, considering the language, surrounding circumstances, and commercial purpose.
4. Weighing Different Forms of Evidence
4.1 The Primacy of Contemporaneous Documents
Where reliable contemporaneous documents conflict with subsequent oral testimony, courts typically accord greater weight to the documents. As Lord Goff observed in Armagas Ltd v Mundogas SA [1986] AC 717 at 757:
"The judge's task is to assess the testimony of the witnesses but also to evaluate it in light of the contemporaneous documentation, the pleaded case and the inherent probability or improbability of the competing cases."
This principle reflects recognition of memory's fallibility and the fact that documents are typically less susceptible to the distorting effects of time, bias, and suggestion. However, this does not amount to an absolute rule that documentary evidence always prevails. Documents may be ambiguous, incomplete, or even inaccurate, and oral evidence may convincingly explain apparent inconsistencies.
4.2 Reconciling Conflicts in Evidence
When faced with conflicting evidence, courts should first attempt to reconcile apparent inconsistencies. Only when reconciliation is impossible should the court determine which evidence to prefer.
In Doherty v Sampey [2023] WASC 10, Allanson J demonstrated this approach when evaluating contradictory accounts about whether certain agreements were loans or property sales. The court reasoned:
"Although Norris and Doherty were uncertain in their recollection of these events, I am satisfied that they would have remembered an agreement to sell the Fanfare premises and 720 Albany Highway. Their evidence that it was a loan that was discussed and agreed is consistent with later documents, and I accept it."
This analysis shows the court drawing on probability (the likelihood that parties would remember selling property), consistency with documentary evidence, and the inherent plausibility of competing accounts to resolve the conflict.
4.3 Absence of Evidence: Jones v Dunkel Considerations
The absence of expected evidence may, in appropriate circumstances, permit an inference that the missing evidence would not have assisted the party who failed to adduce it. This principle, derived from Jones v Dunkel (1959) 101 CLR 298, applies where:
A party fails to call a witness who would be expected to be called if their evidence would assist that party;
The witness's evidence would have elucidated a matter; and
No satisfactory explanation is given for the failure to call the witness.
Similar principles apply to documentary evidence that would naturally be expected to exist but is not produced.
However, the principle has important limitations. As clarified in Kuhl v Zurich Financial Services Australia Ltd (2011) 243 CLR 361 at [63]-[64], the rule "cannot be employed to fill gaps in evidence, or to convert conjecture and suspicion into inference." It does not operate as a substantive rule of law but as a permissible inference that may, not must, be drawn depending on the circumstances.
In Ng v Sevastos [2024] WADC 75 at [155]-[156], the court noted the absence of evidence from defendants regarding the source of funding for certain payments or their purpose if unrelated to the disputed property development. This absence strengthened the plaintiff's case by leaving the plaintiff's explanation unchallenged and unsupplanted by any alternative account.
5. Expert Evidence: Special Considerations
5.1 Admissibility versus Weight
The assessment of expert evidence involves two distinct inquiries:
Admissibility - whether the evidence satisfies legal thresholds for admission
Weight - the probative value to be accorded to the evidence once admitted
This section focuses on the latter, assuming admissibility requirements have been met.
5.2 Evaluating Expert Opinions
Expert evidence should be assessed with reference to:
5.2.1 Qualifications and Specialized Knowledge
The expert's qualifications must be relevant to the specific opinion offered. Expertise in one field does not necessarily qualify a witness to give opinions in related but distinct areas.
In Doherty v Sampey [2023] WASC 10, Allanson J identified instances where an expert valuer had "strayed from his proper role" by making deductions from signatures that went "beyond his accepted expertise." While this did not entirely invalidate the expert's evidence, it affected the weight given to those specific opinions.
5.2.2 Factual Foundation
An expert opinion is only as reliable as the facts upon which it is based. Courts should scrutinize:
Whether the expert had all relevant information
Whether the factual foundation was accurate and complete
Whether assumptions made by the expert are supported by evidence
Allanson J's critique in Doherty v Sampey [2023] WASC 10 of an expert valuer's report illustrates this point. The court found that "the factual foundation for the opinions expressed... was not established" and that it was impossible to "ascertain the extent to which [the expert] acted on information... which was not included in the letter of instruction, and was not otherwise proved."
5.2.3 Reasoning Process
The expert's reasoning process should be transparent, logically sound, and based on methodologies accepted within the relevant field. Courts should be skeptical of opinions that:
Fail to explain underlying reasoning
Rely on unsupported assertions
Do not address contrary evidence or alternative explanations
Employ novel or contested methodologies without adequate justification
5.2.4 Independence and Objectivity
The expert's role is to assist the court, not to advocate for a party. Evidence of bias, partisanship, or lack of objectivity diminishes the weight of expert testimony. Indicators may include:
Selective use of data
Failure to acknowledge limitations or uncertainties
Dismissal of contrary viewpoints without adequate analysis
A history of consistently testifying for one side
Financial arrangements that could incentivize particular outcomes
5.3 Conflicting Expert Evidence
When experts disagree, courts should not simply count opinions or choose the expert who appears most confident or credible. Instead, the court should engage with the substance of competing opinions, considering:
Which opinion is better supported by established facts
Which expert provides more transparent and thorough reasoning
Whether one expert possesses greater relevant expertise
Whether one expert has considered and addressed the other's methodology
In Doherty v Sampey [2023] WASC 10, Allanson J carefully evaluated competing valuation evidence, identifying specific methodological flaws and factual deficiencies in each expert's approach before determining which aspects of each opinion to accept.
6. Practical Guidance for Evidence Assessment
6.1 Applying the Balance of Probabilities
The balance of probabilities standard requires the court to determine whether it is more likely than not that the fact in issue occurred. This involves weighing the evidence for and against the proposition, not merely identifying possibilities.
When applying this standard:
The court must feel an actual persuasion of the fact's existence
The fact must be proved by evidence, not conjecture or speculation
The more serious the allegation, the more carefully the evidence should be scrutinized (Briginshaw principle)
The degree of persuasion required varies with the gravity of the facts alleged and their inherent probability
6.2 Addressing Cognitive Biases
Decision-makers should be aware of common cognitive biases that can affect evidence assessment:
6.2.1 Confirmation Bias
The tendency to search for, interpret, and recall information that confirms pre-existing beliefs while giving disproportionately less attention to information that contradicts them. To counteract this bias, courts should:
Actively consider alternative explanations
Test provisional conclusions against contrary evidence
Consider the evidence from multiple perspectives
6.2.2 Anchoring Bias
The tendency to rely too heavily on the first piece of information encountered. To mitigate this:
Reserve judgment until all evidence has been considered
Consciously revisit initial impressions in light of subsequent evidence
Consider the evidence in different sequences
6.2.3 Hindsight Bias
The tendency to perceive past events as having been more predictable than they actually were. To address this:
Evaluate decisions based on information available at the time
Avoid imposing unrealistic standards of foresight
Recognize the difference between actual and apparent predictability
6.2.4 Availability Heuristic
The tendency to overestimate the likelihood or importance of things that come readily to mind. To counter this:
Consider whether vivid or memorable evidence is being given disproportionate weight
Ensure all relevant evidence is considered, not just the most salient
Be attentive to potentially important but less dramatic evidence
6.3 Giving Reasons
Comprehensive, reasoned judgments serve multiple purposes:
Demonstrating to the parties that their evidence has been considered
Enabling appellate courts to understand the basis for findings
Promoting public confidence in the administration of justice
Providing guidance for future cases
Effective reasons should:
Identify the key factual issues
Explain the evidence relevant to each issue
Address significant conflicts in the evidence
Articulate why certain evidence was preferred over other evidence
Connect the findings to the applicable legal principles
In Doherty v Sampey [2023] WASC 10, Allanson J exemplified this approach by explicitly acknowledging the evidentiary challenges presented by events occurring years earlier, explaining his method for resolving conflicts in the evidence, and providing detailed reasoning for his findings on contested issues.
7. Conclusion
The assessment of evidence in civil proceedings remains an art informed by legal principle rather than a mechanical process. It requires judges to bring to bear their knowledge of human behavior, understanding of evidentiary principles, and capacity for logical reasoning to determine where the truth most likely lies.
The task is inherently evaluative and discretionary, but not arbitrary. By applying established principles consistently, acknowledging the strengths and limitations of different forms of evidence, and providing transparent reasoning, courts can ensure that findings of fact are as reliable and just as the imperfect nature of human fact-finding allows.