The case required interpretation of (mainly) s 86D(2) of the Sentencing Act 2002:
(2) Despite any other enactment, if, on any occasion, an offender is convicted of 1 or more stage-3 offences other than murder, the High Court must sentence the offender to the maximum term of imprisonment prescribed for each offence.
It was universally acknowledged that in this case the result of application of a literal interpretation of this subsection was well beyond excessive punishment for the offence and it would shock the conscience of properly informed New Zealanders. This level of punishment was, in this case, a breach of s 9 of the New Zealand Bill of Rights Act 1990:
9 Right not to be subjected to torture or cruel treatment
Everyone has the right not to be subjected to torture or to cruel, degrading, or disproportionately severe treatment or punishment.
Does the phrase in s 86D(2), “Despite any other enactment” include s 9 of the Bill of Rights?
Deciding this can require considering an interpretive provision of the Bill of Rights, s 6:
6 Interpretation consistent with Bill of Rights to be preferred
Wherever an enactment can be given a meaning that is consistent with the rights and freedoms contained in this Bill of Rights, that meaning shall be preferred to any other meaning.
Here, the phrase “can be given” is important. How big a stretch is permitted by this phrase?
The role of s 6 is not necessarily central to reasoning, because the common law has parallel interpretive tools, particularly the principle of legality (discussed here on 11 February 2021 in relation to D (SC 31/2019) v Police  NZSC 2 ). These parallel tools may be used in combination, or separately.
In this appeal the majority judges were Winkelmann CJ, O’Regan and Arnold JJ jointly, and Glazebrook J.
Winkelmann CJ reasoned that s 6 goes beyond the principle of legality , describing it as a powerful interpretive obligation . Noting that the common law permits, in appropriate circumstances, the reading-in and reading-down of legislation -, and remembering that the result must not be a refusal to apply legislation , she concluded that an exception can be read-in to s 86D(2), -. This was consistent with the purpose of the provision  and it applied only where s 9 of the Bill of Rights would otherwise be breached . Further, where the exception applies and ordinary sentencing principles come into play, these are supplemented by a principle requiring a stern sentencing response to such recidivism .
On the other hand, O’Regan and Arnold JJ relied primarily on the principle of legality as permission for reading-in the exception to s 86D(2). They pointed out  that it would have been easy for Parliament to have specified that the provision applied despite the Bill of Rights. Section 6 requires a similar approach to that adopted under the common law principle of legality . After surveying decisions they concluded  that apparently unrestricted general words are not sufficient to displace presumptions reflecting core legal values. There are more such values than are included in the Bill of Rights, and in this sense the principle of legality is wider in scope than s 6 . Explicit statutory language is required to override the right protected by s 9 . A rights-consistent meaning of s 86D(2) can be given under s 6 without defeating Parliament’s purpose . This conclusion is supported by another principle of interpretation: that legislation should be read, so far as possible, as being consistent with New Zealand’s relevant international obligations .
Glazebrook J, agreeing in the result reached by the other majority judges, was careful to say what she was not making any comment about. See footnote 337, para ,  and footnote 348,  and footnote 351, footnote 352. She applied ordinary principles of interpretation, namely the purpose of the legislation , the need for reading-down in the light of the principle of consistency with international law and with fundamental human rights, and the constitutional status of the Bill of Rights , and the principle of legality . She added in footnote 363: “I do not wish to comment on the relationship between s 6 of the Bill of Rights and the principle of legality, except to say that I agree with Winkelmann CJ that s 6 of the Bill of Rights may go further than the principle of legality.” At footnote 366 she did not agree with the Chief Justice’s comments regarding a stern sentencing principle being added because of s 86D(2).
The majority judges agreed that where the read-in exception resulted in the application of ordinary sentencing principles in a particular case (such as this), a discharge without conviction could be considered, although it might only rarely be appropriate. The question of sentence was remitted to the High Court.
The interpretation of s 6 is now delicately poised: Winkelmann CJ  appears to be willing to give it a strong meaning, consistent with Ghaidan v Godin-Mendoza  UKHL 30,  2 AC 557, while William Young J - (the dissenting judge in this appeal) is more conservative, requiring a rights-consistent interpretation to be reasonably available. The other judges appear to be reserving their positions on this issue.
Personally, and I just say this to get you thinking, my view at present is that the interpretation of s 6 is only a delicately poised issue because Lord Cooke refused to accept he had been wrong in Phillips.