[1] The judgment of the Supreme Court of New Zealand was concerned with the proper interpretation of article 33 of the United Nations Convention Relating to the Status of Refugees 1951 and section 72 of the Immigration Act 1987.

No Contracting State shall expel or return ("refouler") a refugee in any manner whatsoever to the frontiers of territories where his life or freedom would be threatened on account of his race, religion, nationality, membership of a particular social group or political opinion.However paragraph 2 of article 33 states that the benefit of this protection may not be claimed by a refugee, "whom there are reasonable grounds for regarding as a danger to the security of the country in which he is, or who, having been convicted by a final judgment of a particularly serious crime, constitutes a danger to the community of that country."

In conclusion on this point the Court held, We accordingly conclude that the judgment or assessment to be made under art 33.2 is to be made in its own terms, by reference to danger to the security, in this case, of New Zealand, and without any balancing or weighing or proportional reference to the matter dealt with in art 33.1, the threat, were Mr Zaoui to be expelled or returned, to his life or freedom on the proscribed grounds or the more specific rights protected by the New Zealand Bill of Rights Act 1990 read with the International Covenant on Civil and Political Rights and the Convention against Torture and other Cruel, Inhuman or Degrading Treatment or Punishment.

Those rights in turn are to be interpreted and the powers conferred by s 72 are to be exercised, if the wording will permit, so as to be in accordance with international law, both customary and treaty-based.

"[10] What this means is that state parties to these conventions are unable to expel people from their territories if doing so would expose that person to a danger of being tortured.

Neither could a party-state expel, extradite, or return (refouler) a refugee if their race, religion, nationality, social group, or political opinion meant that their life or freedom would be under threat.

[15] Justice Keith cited this reason for this expansion by reference to paragraph (b) of the Bill of Rights' title which "says that it is an Act to affirm New Zealand's commitment to the ICCPR"[16] However what makes Zaoui v Attorney-General (No 2) so significant is the final paragraph that creates the obligation on decision makers to not certify or advise in favour of deportation under section 72 "if they are satisfied that there are substantial grounds for believing that, as a result of that deportation, the person would be in danger of being arbitrarily deprived of life or of being subjected to torture or to cruel, inhuman or degrading treatment or punishment.

Commentator Rodger Haines QC is critical of the Court's decision, believing that it has "erected an apparently absolute bar to expulsion from New Zealand no matter how grave a threat the individual might be to the security of the nation or to its community.

One such practice is that of legitimate expectation[19] – where an authority could indicate that they do indeed intend to act inconsistently with an international obligation and therefore override the Court's presumption.

"[26] It is important to note that the judiciary is not solely responsible for the increase in this approach, the executive branch of Government entered into these international obligations and Parliament implemented statutes that gave power to those obligations with the New Zealand Bill of Rights Act affirming New Zealand's commitment to the ICCPR[27] and sections that allude to terms of Conventions like Part 4A of the 1987 Immigration Act.

In saying this, the Court's "expansive approach in Zaoui to the application of the presumption of consistency thus reflects a posture of profound receptivity to international law as a source of authority within the domestic legal system.

Since Zaoui, New Zealand's Parliament has followed the judiciary's lead by codifying the practices of the conventions and the ruling of the Supreme Court within part 5 of the Immigration Act 2009.

[29] This is particularly evident in sections 130 and 131 which cover "protected persons" status and the mandatory human rights considerations that a decision maker must consider.