In deciding whether evidence is relevant, the trial judge is neither required nor permitted to make any assessment of whether the jury would or might accept that evidence, but must proceed on the assumption that it will be accepted: Adam v The Queen (2001) 207 CLR 96 at [22], [60] (Gleeson CJ, McHugh, Kirby and Hayne JJ); R v Shamouil (2006) 66 NSWLR 228 at [60]–[62] (Spigelman CJ, Simpson and Adams JJ agreeing). The same assumption should be made where the judge is also the tribunal of fact. The test of relevance — that the evidence could rationally affect (directly or indirectly) the assessment of the probability of the existence of a fact in issue in the proceeding — directs attention to the capability rather than the weight of the evidence to perform that task. However, the issues of credibility or reliability may be such a particular case that the judge may rule that it would not be open to the jury to conclude that the evidence could perform that task: R v Shamouil at [62]–[63]; DSJ v R (2012) 84 NSWLR 758 at [8] (Bathurst CJ), [53]–[56] (Whealy JA, Bathurst CJ, Allsop P, McClellan CJ at CL and McCallum J agreeing). In such a case, the effect of the evidence on the probability of the existence of a fact in issue would be nil, and it would not meet the criterion of relevance: IMM v R (2016) 257 CLR 300 at [39] (French CJ, Kiefel, Bell and Keane JJ).

The definition of relevance in s 55 reflects the common law: Washer v Western Australia (2007) 234 CLR 492 at [5], n 4 (Gleeson CJ, Heydon and Crennan JJ). The threshold test is whether there is a logical connection between the evidence and a fact in issue: Papakosmas v The Queen (1999) 196 CLR 297 at [81] (McHugh J). The requirement that the evidence have the capacity to rationally affect the assessment of the probability of the existence of a fact in issue is significant; it is necessary to point to a process of reasoning by which the evidence could do so: Washer v Western Australia at [5]; Evans v The Queen (2007) 235 CLR 521 at [23] (Gummow and Hayne JJ). Where the effect of the evidence is so ambiguous that it could not rationally affect the assessment of the fact in issue, the evidence is irrelevant: Lithgow City Council v Jackson (2011) 244 CLR 352 at [26] (French CJ, Heydon and Bell JJ).

Evidence which is relevant has the capability to affect the assessment of the probability of the existence of a fact in issue, so is by definition “probative”; but neither s 55 nor s 56 requires that evidence be probative to a particular degree for it to be admissible: IMM at [40]. Evidence that is of some, even slight, probative value, may be relevant and therefore prima facie admissible: IMM at [40]. That is so notwithstanding that the evidence may ultimately be categorised by the tribunal of fact as carrying no weight: IMM at [38]; BBH v The Queen (2012) 245 CLR 499 at [97]–[104] (Heydon J); [152], [158]–[160] (Crennan and Kiefel JJ), [194]–[197] (Bell J). Moreover, the tribunal of fact is entitled to assess the particular piece of evidence by having regard to the whole of the evidence in the light of the issues at trial: BBH at [196] (Bell J). Where there is an issue regarding the authenticity of a document, it may still be admissible if it is relevant or arguably so. This is so as long as there is material from which its authenticity may reasonably be inferred. That material will include what may reasonably be inferred from the document itself: Australian Competition and Consumer Commission v Air New Zealand Ltd (No 1) (2012) 207 FCR 448; see also [4-0220].

The general proposition stated by French CJ in BBH (at [57] and [58]) that “equivocal” evidence is not relevant and should thus be rejected (see also Hayne J at [80]–[81], Gummow J at [61]) was not supported by the majority decisions: see Criminal Trial Courts Bench Book Special Bulletin 26.

In a criminal case, the facts in issue are the “ultimate facts which establish the elements of the offence or offences charged together with such other facts the existence of which may be probative of the existence of those ultimate facts”: McNamara v The King (2023) 280 CLR 201 at [69] (Gageler CJ, Gleeson and Jagot JJ); Smith v The Queen (2001) 206 CLR 650 at [7] (Gleeson CJ, Gaudron, Gummow and Hayne JJ). The prosecution may set out to establish that an accused had a motive to commit an offence charged. Motive may rationally affect the assessment of the probability of the existence of one or more of the elements of an offence; evidence that tends to establish motive, therefore, may rationally affect such assessment: HML v The Queen (2008) 235 CLR 334 at [5] (Gleeson CJ).

In a civil case, “the facts in issue … emerge from the pleadings, which, in turn, are framed in the light of the legal principles governing the case. Facts relevant to facts in issue emerge from the particulars and the evidence”: Goldsmith v Sandilands [2002] HCA 31 at [2] (Gleeson CJ).

The evidence must affect the probability of the existence of the fact sought to be proved. In a case where it was alleged that the accused had acted in self-defence, evidence that the victim had previously carried a firearm did not go to the probability that he was carrying a firearm on the occasion in question: Elias v R [2006] NSWCCA 365 at [26] (Simpson J, McLellan CJ at CL and Rothman J agreeing); although it would have been relevant to the issue of his tendency to carry such a weapon (at [31]); R v Cakovski [2004] NSWCCA 280 at [36], (Hodgson JA), [56]–[57], (Hulme J), [70] (Hidden J) (see [4-1610]) doubted.

Observing how the accused walked or how he spoke certain words would be relevant to the identification of the accused as the person seen and heard by the witnesses, but dressing the accused in the clothing worn by the person seen by the witnesses gave no assistance to the jury in determining whether he was the person seen by the witnesses: Evans v The Queen at [27].

Where evidence of identification depends on a photograph taken by a security camera, it is for the jury to determine whether the accused is shown in the photograph, and evidence by a police officer that he had made such an identification from the photograph cannot logically affect the jury’s task: Smith v The Queen at [11]. A complainant who has no recollection of an alleged sexual assault cannot be asked whether her interview video recorded shortly after the event demonstrated that she had consented: R v TA (2003) 57 NSWLR 444 at [6] (Spigelman CJ), [24], [26] (Adams J).

The Law Reform Commission’s intention — that only a minimal logical connection between the evidence and the fact in issue was required, sufficient to make the fact in issue more probable or less probable than it would be without the evidence (ALRC Report 26, vol 1) — was accepted as the appropriate interpretation of s 55, in R v Clark [2001] NSWCCA 494 at [111]–[112] (Heydon JA). Evidence is either relevant or it is not; no discretion falls to be exercised in determining relevance: Smith v The Queen at [6]; Phillips v The Queen (2006) 225 CLR 303 at [50].

The “probative value” of evidence and the “credibility” of a witness are defined in the Dictionary to the Evidence Act. Section 55(2) does not of itself make the credibility of a witness relevant to a fact in issue in the proceeding unless it is of such a nature as to tend rationally and logically to weaken confidence in the veracity of the witness: R v Slack [2003] NSWCCA 93 at [31]–[34] (Sheller JA, Woods CJ at CL and Smart AJ agreeing).

The probative effect of telling a lie is logically the same in a civil case as it is in a criminal case: Barrett Property Group Pty Ltd v Carlisle Homes Pty Ltd [2008] FCA 375 at [75]–[76] (Heerey J).

If evidence is not relevant, it is not admissible: s 56(2); Smith v The Queen (2001) 206 CLR 650 at [12].

This section raises the vexed question as to whether a miscarriage of justice may have occurred if no objection is taken to “irrelevant evidence”: see [4-0400] and also [4-1630]. The better view is that “not admissible” means “not admissible over objection”, although in a criminal trial the judge has an overriding duty to ensure a fair trial and to prevent a miscarriage of justice: Perish v R (2016) 92 NSWLR 161.

Evidence probative of the existence of one fact in issue in a proceeding is admissible in the totality of the proceeding — that is, if admitted or not otherwise limited, including in relation to any fact in issue between parties to the proceeding other than the party adducing it: McNamara v The King (2023) 280 CLR 201 at [67]. In the case of a criminal proceeding constituted by a joint trial on a joint indictment, this means that any evidence relevant to the case against one co-accused is available to be used against any other co-accused, unless and to the extent that the admission of the evidence is excluded, or the use of the evidence is limited, by or under some other section (eg, ss 135–137): McNamara at [69]. Evidence is not unfairly prejudicial against another defendant within the meaning of s 136 only because it is not relevant to the case against that defendant, although it may be regarded as so prejudicial if the case is tried with a jury: Johnstone v State of NSW [2010] NSWCA 70 at [102]–[103] (Beazley, McColl and Young JJA agreeing).

Whilst evidence relating to the prior sexual history of the complainant in relation to a prescribed sexual offence may be relevant, statutory proscriptions may make it inadmissible: see Criminal Procedure Act 1986 (NSW), s 294CB(2)–(3); see also Criminal Trial Courts Bench Book at [5-100] and ff.

This provision is similar to the practice before the Evidence Act of admitting evidence subject to relevance: Nodnara Pty Ltd v Deputy Commissioner of Taxation (1997) 140 FLR 336 at 338 (Young J). Where the relevance of particular evidence is initially unclear, it remains appropriate under the Act for evidence to be admitted in a non-jury case subject to relevance, and for a ruling to be made as to its effect at the conclusion of the case: Merrylands Bowling, Sporting and Recreation Club Ltd v P & H Property Services Pty Ltd [2001] NSWCA 358 at [35] (Rolfe AJA, Hodgson JA and Young CJ in Eq agreeing).

The decision of National Australia Bank Ltd v Rusu (1999) 47 NSWLR 309 (Bryson J) generated debate about whether s 57 permits the issue of a document’s authenticity to be postponed until after its relevance has been determined, and whether a question of authenticity is a question as to the relevance of documents in relation to which inferences can be drawn under s 58(1). Bryson J held that relevance depends on the authenticity of the evidence, such that the latter must be established before relevance can be determined: at [19]ff. Rusu was held to be plainly wrong by Perram J in Australian Competition and Consumer Commission v Air New Zealand Limited (No 1) (2012) 207 FCR 448 at [99]ff, and was expressly overruled in Gregg v R [2020] NSWCCA 245 at [362]–[372] (Bathurst CJ), [713]–[716] (Leeming JA). The preferred approach is that taken by Perram J in ACCC v Air New Zealand, that if a document is alleged not to be authentic it may be relevant as long as there is material from which its authenticity may reasonably be inferred, which, by s 58(1), includes what may reasonably be inferred from the document itself.

Section 57(2) (“Provisional relevance”) permits the use of evidence that a party to the proceedings is a member of a joint criminal enterprise for the purpose of determining whether or not he or she is in fact a member of that enterprise. The Law Reform Commission explained (at ALRC Report 26, vol 1, at [646] “Conspirators”) that such evidence — tendered on the basis that it is reasonably open to the tribunal of fact to find that he or she is a member of the enterprise — is not tendered for a hearsay purpose and thus is not caught by the hearsay provisions in the Act; cf Ahern v The Queen (1988) 165 CLR 87 at 93–94, 99–100; R v Masters (1992) 26 NSWLR 450 at 460–461. See also s 87(1)(c) (“Admissions made with authority”) at [4-0870].

See also s 183, which permits any reasonable inferences to be drawn from a document where a question arises about the application of a provision of the statute in relation to that document.