Credibility, demeanour, disclosure: deference and inconsequence: Cox v R [2023] UKPC 4

The deference of an appeal court to demeanour-based assessments of a witness’s credibility at trial is illustrated in Cox v R (Turks and Caicos Islands) [2023] UKPC 4, at [31], [34], [40].

There is always a kind of residual feeling that, even so, the credibility assessment may have been wrong. Deference avoids the need for appellate courts to deal with this. Plainly, the law has to be pragmatic about what risks are acceptable. Without challenging the correctness of the conclusion of this appeal, where circumstances supported the credibility assessment (see at [34(iv)], [46]-[47], [49]), we can still be left wondering about some general issues.

How reliable is an assessment of credibility based on demeanour? What does science tell us about this? Is an articulated warning about the need for caution in assessing credibility based on demeanour sufficient to counteract the risk of error, or might it be just a formulaic ritual?

Is it appropriate for an appellate court to defer to credibility assessments made at trial? Will technology, such as video recordings of trials, diminish the so-called advantage that the trial court has? Will the recently confirmed ability of appellate courts to reach what are really verdicts mean that appeals against conviction become replays of trials?

Should corroboration be required where the credibility of a witness is of central importance?

Another point brought to mind by this appeal is the inability of the courts to provide a remedy for unacceptable failure of timely disclosure if it does not affect the fairness of the trial (see [43]-[44]). Does unacceptable failure have no consequence? What does “unacceptable” mean?

Update: on 7 March 2023 the Chief Judge of the New Zealand High Court issued a practice note on disclosure in criminal cases (HCPN 2023/1). In the absence of an express power to punish for breach of the protocol, it may be assumed that relevant powers are costs orders under the Criminal Procedure Act 2011, s 364, and fines or imprisonment under the Contempt of Court Act  2019, s 16.

Hypothetical facts demonstrating the invalidity of laws: R v Hills, 2023 SCC 2

Courts in some legal systems can declare parliamentary legislation invalid. In at least some others courts may make a declaration that legislation is inconsistent (a DoI) with rights, but may take no further action against such legislation.

Deciding whether to declare legislation invalid can involve reasoning that has similarities to a debate held in the course of the production of a statute. Indeed, the reasoning process of the court may look - at least in part - very like the reasoning that a select committee may use in scrutinising a proposed enactment. This involves considering its implications by referring to hypotheticals.

In contrast, when a court is deciding whether to issue a DoI, it does not engage in a hypothetical exercise. It is the facts presented by the plaintiff, and accepted by the court, that form the ground for the DoI decision.

R  v Hills, 2023 SCC 2 illustrates engagement with hypotheticals where the validity of legislation had to be determined. The consideration of the application of the law to a reasonably realistic hypothetical led to a declaration that the impugned law was of no force and effect, and this declaration applied retrospectively.

However, where the most that the courts may do is issue a DoI, the approach (in New Zealand) is as illustrated in Attorney-General v Taylor [2017] NZCA 215, confirmed in Attorney-General v Taylor [2018] NZSC 104 and further illustrated in Make it 16 Inc v Attorney-General [2022] NZSC 134. When a DoI is issued there are procedural consequences for the legislature, provided for by ss 7A and 7B of the New Zealand Bill of Rights Act 1990. Those provisions were added to the Bill of Rights on 30 August 2022.

Although a DoI does not itself provide a remedy for the plaintiff in the instant case, the court may use interpretative techniques to reach a favourable result. For example, where the (since repealed) three strikes sentencing regime created an obvious injustice, the court was able to put the defendant within an exception to that regime: Fitzgerald v R [2021] NZSC 131 (noted here on 8 October 2021).

In Hills, the law was successfully challenged on the basis of how it would apply to others. The mandatory minimum sentence was found to be grossly disproportionate to the appropriate sentence for the same offence committed in a hypothetical set of facts in which the appellant’s hunting rifle was replaced with a paintball gun. The appropriate sentence was less than the mandatory minimum.

Unsuccessful challenges to the validity of legislation were made in the companion appeal, R v Hilbach, 2023 SCC 3. Here the offence was narrowly defined so there was little scope for hypotheticals that would call for sentences that would make the mandatory minimum sentence grossly disproportionate.

Appropriate recognition of mitigating factors in sentencing for serious offending: Philip v R [2022] NZSC 149

Sometimes, the person being sentenced has changed, through efforts at rehabilitation and new family connections, into a very different person from the one who committed the offence.

This could present a problem where sentence levels are prescribed in a systematic way which begins with a starting point based on the seriousness of the offence and the offender’s role. The starting point ascertained in this way could diminish the mitigating effect of the offender’s personal circumstances, because it may move the result towards a very high end sentence.

Nevertheless, judges can arrive at a sentence that is just in the particular circumstances. An illustration is Philip v R [2022] NZSC 149 (16 December 2022), where the offender had transported a total of 6 kg of methamphetamine from Auckland to Wellington.

Here, the Supreme Court ultimately accepted the mitigating discounts that had been applied by the sentencing judge in the High Court [57]. These were (at [13], [15]) 20 per cent for guilty plea, 30 per cent for personal circumstances (difficult background, mental health issues, demonstration of genuine remorse and significant steps towards rehabilitation by overcoming addiction), 10 per cent for the impact that a sentence of imprisonment would have on the offender’s young family, giving a total deduction of 60 per cent. Added to this was a deduction of 6 months for a period on electronically monitored (EM) bail.

All those deductions were from the starting point, and it was the starting point that was the most controversial aspect of this case. The High Court assessed this as 6 years’ imprisonment. The Court of Appeal, on appeal by the Solicitor-General, assessed the starting point as nine years (but because the guilty plea had been in response to a sentence indication of eight years, the CA accepted eight years as the starting point) [17]. The SC accepted the the HC’s assessment of starting point but added that it could be said to be a little below what was appropriate [41].

These differences arose from different perceptions of the offender’s role in the offending, a topic recently addressed by the SC in Berkland, summarised at [19] (see my note on 8 December 2022).

Was it necessary here to strain the starting point downwards to achieve a just sentence? The SC arrived at a sentence (not to be regarded as a precedent [60]) [1] that ensured Mr Philip’s immediate release from prison. He had served 7 months of the 12 months’ home detention imposed in the HC. Two judges, while agreeing in the outcome of the appeal and on all but one of the points in the reasoning of the majority [62], thought that the CA should have identified the appropriate sentence (it had assessed this as only two years and 11 months’ imprisonment, as the majority record at [45]) but then the CA should have dismissed the Solicitor-General’s appeal [74]. That would have avoided using a starting point which called into question the utility of the guideline judgments [73].

The implication is that where precedents point to a higher end sentence than seems just in the instant case, the court should ask whether enhanced recognition is deserved for changes in the offender’s life that demonstrate a negligible risk of reoffending. Familial connections, especially the effect of a child’s loss of a parent through imprisonment, are relevant in addition to the offender’s significant efforts at rehabilitation. There may be occasions where higher percentage discounts could be given than were applied in this case.

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[1] Arguably, it is contrary to the rule of law for a court to say that its decisions are not precedents: see John Gardner, Law as a Leap of Faith (OUP, 2012), p 210: “It is a violation of the requirements of the rule of law for a judge to … [deny] that there is a rule (in other words, claiming that the case under decision is being decided only ‘on its particular facts’).”

Has the voluntariness of confessions requirement become too complex? Beaver v R, 2022 SCC 54

When the highest court splits 5-4 on basic issues of evidence law, one has to ask whether something is fundamentally wrong with the way the issues are addressed by the law.

Reading Beaver v R, 2022 SCC 54 (9 December 2022) gives rise to questions like the following:

Is there too much room for the appellate court to defer to the findings of the first court in which the issues were determined? Arguably, deference erodes a defendant’s appeal rights. It is the judgement [spelt here with that middle e to emphasise reference to the mental process] of the appeal judges that should be applied to the issues.

Is the concept of the voluntariness of a confession being overloaded with other issues? Reliability, for example, is different from voluntariness. Does voluntariness really invoke a “delicate balance between individual rights and collective interests in the criminal justice system”? [46] Or was that balance struck a long time ago when it was decided (at common law) that confessions must be made voluntarily if they are to be admissible? Does treating the voluntariness rule as having “twin goals” over-analyse what is really a simple point? [1]

Are facts to be assessed holistically or does a “clean or fresh start” make previous breaches of rights irrelevant? Is it fair to assess police conduct disjunctively when the defendant experienced it conjunctively? Should the concept of a clean start be rejected, as the minority would do? [140] Or does it blend in with the holistic approach as the majority suggest at [99]?

When courts assess the reasonableness of an officer’s belief that the defendant has committed an offence, are they really making an objective assessment? Do judges inevitably put themselves in the place of a reasonable person, and in effect using the criterion of a reasonable judge are they less likely to disagree with the first instance judge?

Does the public interest factor require taking account of more than the seriousness of the alleged offence and the importance of the challenged evidence to the prosecution’s case? Does the public interest weigh on both sides of the balance (as it is in the public interest that everyone who is charged with an offence has their rights complied with, as well as that allegations of serious offences should be tried) so that it is too nebulous to be a useful consideration apart from the seriousness of the alleged offence and the centrality of the evidence? Is the reference to “cut both ways” at [130] unbalanced (compare my comment on this metaphor on 11 November 2020)?

Both the majority and the dissenting judgments make good sense in their own ways, so one must consider their respective premisses, and ask whether the problem is with the complexity of the law.

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[1] Funnily enough, in New Zealand our Evidence Act 2006 does not mention the voluntariness of confessional statements, which unless one thinks the Act is a code means that the topic is left to the common law. This could be sensible, for if it were in the Act, a requirement of voluntariness could later be repealed, which would have the consequence that the common law on the point would not be revived: see the Legislation Act 2019, s 32(2)(b). The provision concerning statements obtained by oppression (Evidence Act 2006, s 29) refers to a different issue: the propriety of the conduct of the interrogator. Voluntariness, however, is an issue directed to the volition of the speaker. Involuntariness occurs when a sleeping person speaks, or when a hypnotised person speaks, or when an anaesthetised person speaks, or when a person speaks when their volition is removed by a drug, for example the ravings of an alcoholic directed at an imaginary listener are probably involuntary. Tourette syndrome can produce involuntary speech. Voluntariness is a scientific question. Speech produced by torture is not involuntary, but it is inadmissible because of the improper conduct of the interrogator. The common law rule about confessions having to be "voluntary" (Ibrahim v R [1914] AC 559, 609) is best stated without that word: no statement made by an accused is admissible unless it is affirmatively shown to have been made without fear of prejudice or hope of advantage exercised or held out by a person in authority. That is the sense in which the term "voluntary" was used in Ibrahim: see R v Rennie [1982] 1 All ER 385. The common law rule has two parts: one concerns the behaviour of the person in authority, and the other concerns the effect of that behaviour on the accused. Does Canadian law, in using voluntariness as the touchstone (Beaver at [47], [57]) over-emphasise the effect on the accused, while (it might be said) New Zealand law neglects that except to the extent of requiring that the statement was "influenced"(s 29) by oppression or was made "in consequence" of the improper conduct of the interrogator (s 30(5))? At least the objective behaviour of the interrogator is likely to be less imponderable than the accused's voluntariness.

Sentencing methamphetamine dealers: the offender's role and background: Berkland v R [2022] NZSC 143

In Berkland v R [2022] NZSC 143 (7 December 2022) the New Zealand Supreme Court clarified several aspects of sentencing for dealing in methamphetamine. Some of the points addressed are applicable to sentencing generally.

A person who deals in methamphetamine may be described as having a significant role in the offending, as opposed to a lesser role or a leading role. The significant role comes between the alternatives, so there will be instances of significant role which are closer to a leading role, and others to a lesser role, and some of middling status in the significant role category. But the categories are porous, not siloes (at [65]).

A distinction is now clarified between those in the significant role category who have a management role and those who have an operational role. Managers are at the more serious end of the significant range, and the offending of operators is of lesser seriousness. Managers act under direction of a leader, and this entails directing others in the operation, whether by pressure, influence, intimidation or reward. Their remuneration will be out of proportion to the relatively lesser risks they are exposed to. Operators and those whose role is at the lower end of the significant range are exposed to risks that are greater than their proportionately lesser remuneration (at [68]-[71]).

Another, and more generally applicable, aspect of sentencing addressed in this decision is the required nexus between the offending and potential mitigating factors arising from the offender’s background. Various descriptions of this nexus had been used in the cases, such as an “operative cause” or a “proximate cause”. Those expressions are now replaced by the lower standard of a “causative contribution”, meaning that the offender’s background may have mitigatory effect if it makes a causative contribution to the offending.

The background factors of addiction and of historic deprivation and discrimination were extensively discussed by the Court, as was the use of various sources of information to inform the sentencing judge of relevant matters.

Reducing the randomness of online virtue testing: Ramelson v R, 2022 SCC 44

When can the police legitimately trick people about whom they have no prior knowledge into committing a crime?

And in what circumstances may such trickery be carried out online, as opposed to in a physical space?

The Supreme Court of Canada considered these matters in Ramelson v R, 2022 SCC 44 (24 November 2022).

A finding that the police acted unlawfully, here by entrapping a person into committing an offence, would be grounds for issuing a stay of proceedings. The drastic nature of issuing a stay makes the decision highly contextual.

Although highly contextual - dependent on the particular circumstances of a case - the decision process is structured. Ultimately, stays are issued to preserve the respect and support that the community has for the law. Given that as the ultimate criterion, one would expect that when a stay is necessary, it will be obviously necessary. The eggregiousness of the police tactic used to obtain the evidence should be obvious to most people. So, why have an elaborate decision model?

In Canada, the police can present any person with the opportunity to commit a crime if they conduct a bona fide inquiry. Bona fide means having a reasonable suspicion that offending is occurring over a sufficiently precise space, and having the genuine purpose of investigating and repressing crime [35].

The notion of space might refer to a geographical area in which offending is suspected to be occurring, or it might refer to a communication channel such as a phone number if it is reasonably suspected to be being used for a criminal purpose. And where crime is conducted through the medium of the internet, the space may need to be curtailed to meet the “sufficiently precise” requirement [51].

In Ramelson the investigation was into the grooming of young people for sexual purposes at an internet site that hosted explicit advertisements by young people offering such services. The police covertly posted similar advertisements on the site. To commit the relevant offence, a person had to go to the site, click on an advertisement, and then message a number mentioned in that advertisement. Those three steps in effect sequentially increased the precision with which the space was defined. They served to reduce the randomness of virtue testing that otherwise could have been beyond the bounds of acceptable police conduct [55].

The police advertisements here presented opportunities to commit offences for which there were reasonable grounds to suspect were occurring, and also slightly more serious offences for which there had been no such grounds. In the circumstances this did not matter, because the two kinds of offence were rationally connected and proportionate to each other [69], [94]-[100].

The judgment discusses in detail the various considerations that can be relevant to the definition of an online space [62]-[68].

The significance of error at trial: Awad v The Queen [2022] HCA 36

When is an error at trial sufficient to cause an appellate court to examine the safety of a conviction?

Appellate judges occasionally differ over the significance of an error in the context of a trial.

Context is important because some errors are slips that can be neutralised during a trial, for example where a judge in summing up to the jury on the law accidentally misstates the way the evidence of a defendant must be approached. This error might be corrected, with the correction being adequately emphasised, by further instructions in the same summing up.

Whether adequate correction of this sort of error occurred was the point under appeal in Awad v The Queen [2022] HCA 36 (9 November 2022). The Court, by a 4-1 majority, ordered a new trial. If the prosecution wishes to pursue that opportunity, each side will, no doubt, find useful the issues identified by Gordon and Edelman JJ at [105].

Steward J dissented, in a judgment that, read on its own, is a convincing argument in support of the immateriality of the error in this case. Broadly, and in my words, he reasoned that as perfection tends to be elusive [115], the point is whether the jury was thrown off course by the error [116], and this is to be assessed in the light of the whole of the judge’s instruction to the jury [122]. Here, trial counsel decided that the best course was to pass over the error [120], and the judge had made adequate correction of the mistake [126]. More controversially, Steward J added that “today’s juries have never been so well educated” [131]. Really? In Greek, Latin, Logic? The news media tell us that educational standards are in decline. People are leaving school less literate, less numerate, and consequently more ignorant than (if I may, following Steward J, use the rhetorical device of hyperbole) ever before. Anyhoo, Steward J was able to conclude that an error in directing the jury on the topic of credibility did not matter in this case where the issue was the credibility of one of the defendants.

So much simpler was the approach of the majority, although the existence of two joint majority judgments will make readers wonder why there were two judgments, and what any difference between them might be. Perhaps the difference is that Gordon and Edelman JJ are more discursive (for example at [93]-[95]).

Kiefel CJ and Gleeson J were sensitive to the possibility that the jury was (presumably despite its education) confused by the misdirection [37]. This risk of confusion took the issue beyond that addressed by the majority in the Court of Appeal, to whether on the whole of the record the convictions were inevitable [38].

Gordon and Edelman JJ took the same approach, setting out the law at [78]. They gave three reasons for concluding that the error was a significant one that could have affected the result ([101]-[104], but compare Steward J’s three considerations at [127]-[134]).

Again broadly, as this was a case where the credibility of a defendant’s evidence was material, the appellate court was not, by a majority, in a position to say, on the face of the record of the trial, that the convictions were safe. A new trial was therefore ordered.

Some people may wonder why, in view of the burden and standard of proof, a new trial was ordered. Perhaps the explanation is that it was the judge who threw the spanner into the works, and it was not the fault of the prosecution that the error occurred. It would be unfair to the Crown to deny it a properly conducted trial.

Failure to caution a suspect: R v Tessier, 2022 SCC 35

The Supreme Court of Canada’s decision in R v Tessier, 2022 SCC 35 (14 October 2022) concerns the admissibility consequences of a statement obtained without giving the standard police caution about the right to silence.

This was an issue determined under Canadian common law. It may be compared, by evidence law buffs, to the way the same issue is addressed in the statutory evidence law of New Zealand under the Evidence Act 2006.

The Canadian law gathers together concepts, most of which are familiar: voluntariness, fairness, reliability, balance, repute to the administration of justice, prima facie, beyond reasonable doubt, threats, promises, oppression, trickery, and the so-called operating mind doctrine (which requires that the interviewee exercised a meaningful choice to speak and was not improperly influenced by state action).

These are packed into a decision model that is summarised at [89]. It applies to any person questioned as a suspect, as defined at [81]-[82].

In New Zealand the Practice Note on Police Questioning issued by the Chief Justice requires a caution to be given in the circumstances described in [2]. It applies to anyone in custody, and also to anyone whom a member of the police has sufficient evidence to charge with an offence.

Failure to caution such a person can have forensic consequences, according to whether the admissibility of the uncautioned statement is challenged under s 28 (unreliability), s 29 (influenced by oppression), or s 30 (improperly obtained). The standard on each issue is, for unreliable and improperly obtained statements, the balance of probabilities, and for those obtained by oppression beyond reasonable doubt. Reading each in its context suggests a greater intolerance of oppression than of unfairness.

Here the concern is with investigatory fairness, not trial fairness. In Tessier the  Canadian court notes that fairness is important but it doesn’t exclude other values (at [72]). Similarly, under s 30 the consequences of unfairness in the obtaining of evidence is determined by the balancing exercise described in that section.

The statement was ultimately ruled admissible in Tessier. Would the same result have been arrived at under New Zealand law? (5 marks.)

Three fundamentals of evidence law: R v Schneider, 2022 SCC 34

You wouldn’t expect to find huge differences in the law of evidence between common law legal systems, even where legislation has replaced the common law. So it is reassuring to experience once again the similarity of Canadian evidence law to that in New Zealand: R v Schneider, 2022 SCC 34.

The appeal concerns the law of hearsay. In general terms, the decision framework for determining admissibility can be, and is, put as having three component parts: (1) is the evidence relevant? (2) Is it excluded pursuant to a rule? (3) Should an applicable discretion have been exercised so as to exclude it? [1]

The Supreme Court of Canada split 7-2 on the relevance component. The minority ([89] ff) would have excluded the evidence because it was impossible to determine its relevance as it was too vague to be identified. You have to know what the challenged evidence is before you can decide whether it is relevant. And here, its prejudicial effect necessarily outweighed its probative value ([96]).

The majority, being satisfied that the challenged evidence was relevant, then considered whether it was inadmissible because of the hearsay rule. Here the evidence was of what the defendant himself had said, and unsurprisingly it was not inadmissible hearsay. In New Zealand we don’t apply the hearsay rule to a defendant’s own statements because there are separate provisions in the Evidence Act 2006 covering this. [2]

Then, and this is the only bit that I find incongruous, the third component of the determination was addressed. It was referred to as a “balancing” of probative value against prejudicial effect. [3]

This so-called balancing has a long history in the common law. It isn’t really balancing, because a high risk of improperly prejudicial effect is not needed to make evidence inadmissible when its probative value is high. Improper prejudice usually amounts to a risk that the fact-finder will use the evidence in an improper process of reasoning. If there is that risk, and if it can’t be overcome by judicial instruction, then the evidence will be inadmissible no matter how probative it is.

Even where this discretion is described as a “weighing” exercise, this is a context where weighing is not balancing. But I have said this before, on 8 October 2019, in greater detail. This is just a matter of getting the decision model clear.

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[1] In New Zealand we no longer (since the enactment of our evidence law) use the term "discretion" to describe the decision process, and there is no deference to the trial judge. Instead, the various admissibility decisions in criminal cases are treated as applications of rules and admissibility is a question of law (see R v Gwaze [2010] NZSC 52, noted here on 18 May 2010) and on appeal the appellant is entitled to the unfettered judgment of the appeal court. In that sense it is sufficient to say that in New Zealand the decision framework has only the first two components mentioned in Schneider.

[2] The Evidence Act 2006 largely enacted the New Zealand common law together with the previous legislation (with some changes, such as the provisions concerning expert evidence, compare Ellis v R [2022] NZSC 115 and s 25 of the current Act) on specific topics. The special provisions on the admissibility of a defendant’s own statements (see s 27 and the sections mentioned therein) were necessary to preserve what had been an exception to the common law rule excluding hearsay (see Scheider at [52]).

[3] We have enacted this too: s 8, where it is described as a weighing, and the relevance rule is in s 7.

Tikanga Māori and the common law of New Zealand: Ellis v R (Continuance) [2022] NZSC 114

Today our Supreme Court released two decisions in the Ellis case. The case concerns the convictions in 1993 of the appellant for sexual offending at the Christchurch Civic Creche. The first of the decisions contains the reasons, in separate judgments, for allowing the appeal to continue despite the death of the appellant after the grant of leave to appeal. The second is the substantive decision of the Court in a single judgment quashing all the convictions. I will just mention the first decision here, and I do not try to give a detailed account, as there is no substitute for reading the individual judgments.

The first decision, Ellis v R (Continuance) [2022] NZSC 114, includes important discussions of the relationship between tikanga Māori and New Zealand common law. Fortunately for everyone, the Court has done the hard work of pointing us to the relevant parts of the judgments in its Summary of Reasons, paras [1]-[23].

To what extent is tikanga part of the decision? The reasoning of the judges differed, but fell into two camps. The majority, Glazebrook, O’Regan and Arnold JJ, were able to decide the continuation-of-the-appeal point on factors listed at [8], without requiring those factors to be modified in this case by tikanga concepts which nevertheless “may be relevant” [11]. The minority, Winkelmann CJ and Williams J, were able to “fold in” tikanga concepts into their decision framework [10].

The unanimous approach to tikanga is summarised at [19]: where relevant, tikanga can be “recognised in the development of the common law”. The majority (here, Winkelmann CJ, Glazebrook and Williams JJ) held that the “relationship between tikanga and the common law” will evolve contextually, case by case [21]. Further, “the courts must not exceed their function when engaging with tikanga” [22].

Glazebrook J’s remarks at [126]-[127] describe the current relationship between tikanga and the common law. Winkelmann CJ notes, and agrees, that the role that tikanga will play in the development of the common law is best addressed on a case by case basis [183]. Williams J too stressed the importance of context [261], [266]-[272].

Tikanga was relevant in this case because the convictions adversely affected the mana , among other tikanga considerations, of Mr Ellis and his family: [128]-[135]. Significantly, Mr Ellis was not Māori [136], but expert opinion was that there was nevertheless an impact on his mana [141]. Glazebrook J noted that tikanga may be relevant “particularly if any of the parties involved are Māori” [144], and even where they are not a tikanga perspective may highlight important values [145]-[147].

I do not think that this case supports the view that a separate legal system should be developed, concentrating on tikanga values. Rather, it seems that the common law (where applicable - that is, where not replaced by legislation, which itself may require consideration of tikanga) will evolve and be informed by tikanga where relevant, either by taking it into account on an individual basis, or by adopting it gradually as precedent. The process will be one of enrichment and not of contrast. The courts cannot change tikanga, or rule on what tikanga should be, but they can accept expert opinion on tikanga, just as they can accept expert opinion on, for example, science, without being able to change the science itself. Tikanga can serve to emphasise what is common to everyone.

Update: for an interesting media review of the decision and a collection of commentaries, see this article from Stuff, published on 15 October 2022. I must say that some of the critical comments about judges over-stepping their role and trespassing on what is parliament's business are incorrect. If we think back to how the common law started, when King Henry II sent judges in England on circuit to ascertain and apply local laws, and then required them to hold meetings to thrash out a law that, taking the best of all the ideas, would subsequently be applied across England, we can see how the common law - which is the business of judges and which is always able to be replaced by legislation - can draw upon the best of the ideas circulating in the country and meld them together. If parliament thinks some improvement is necessary, it can pass the appropriate enactments.

Further update: Observations on tikanga are to be found in Smith v Fonterra Co-operative Group Limited [2024] NZSC 5 at [182]-[189]. At [187]: "... tikanga was the first law of New Zealand, and it will continue to influence New Zealand’s distinctive common law as appropriate according to the case and to the extent appropriate in the case. [Footnote: The past and present interface of tikanga and the common law was recently discussed in: Te Aka Matua o te Ture | Law Commission He Poutama (NZLC SP24, 2023)]."