The appellant, Trans-Tasman Resources Ltd (TTR), proposed to mine iron sands in a 66 km² area of the seabed in New Zealand’s Exclusive Economic Zone (EEZ), offshore from Taranaki. TTR held a mining permit issued under the Crown Minerals Act 1991 in respect of its proposed seabed mining activities. In order to carry out those activities, TTR also required marine consents and marine discharge consents under the Exclusive Economic Zone and Continental Shelf (Environmental Effects) Act 2012 (the Act).

In August 2017, TTR was granted marine consents and marine discharge consents by a Decision-Making Committee (DMC) appointed by the Environmental Protection Authority (the EPA). The four-person DMC was equally divided on whether the consents should be granted: they were granted as a result of the casting vote of the DMC Chair. The consents permitted TTR to extract up to 50 million mt of seabed material per annum, and to process that material on an Integrated Mining Vessel (IMV). Some 10 per cent of the extracted seabed material would be retained to be further processed into iron ore concentrate. The remaining material would be returned to the seabed. The 'plume' of suspended sediment that would result from this discharge from the IMV would amount to a discharge of harmful substances for the purposes of the Act, in respect of which TTR required a marine discharge consent. The likely environmental effects of the sediment plume were a central focus of the DMC's assessment of TTR’s application. Other significant environmental effects would include the direct effect of mining on the seabed floor and benthos in the mining area, and the effect on marine mammals and other fauna of the noise of the mining activities.

The first respondents made submissions to the DMC opposing the grant of the consents. They then appealed to the High Court, arguing that the DMC decision was wrong in law on a number of grounds. The High Court held that the consents adopted an 'adaptive management approach', which the Act did not permit in relation to marine discharge consents. The High Court quashed the DMC decision, and referred TTR’s application back to the DMC to consider in light of the High Court judgment: see Taranaki-Whanganui Conservation Board v Environmental Protection Authority [2018] NZHC 2217, [2019] NZRMA 64 (CMI374).

TTR appealed from the High Court decision, arguing that the consents did not adopt an adaptive management approach and should not have been quashed. The first respondents sought to uphold the High Court decision. The first respondents filed cross-appeals, arguing that there were other errors of law in the DMC decision. They said that the High Court should have set the DMC decision aside for those reasons also. They sought an order dismissing TTR’s application for consents under the Act, rather than referring it back to the DMC.

Held: The appeal is dismissed. The High Court’s decision to allow the first respondents' appeal and quash the decision of the DMC is upheld on other grounds. In so far as the first respondents' cross-appeal seeks the appellant’s application for a marine consent and marine discharge consent to be declined, that cross-appeal is dismissed. The appellant’s application is referred back to the EPA to be considered in light of this judgment.

The United Nations Convention on the Law of the Sea (UNCLOS) provides that New Zealand has a duty to protect and preserve the marine environment. New Zealand has the sovereign right to exploit the natural resources of its EEZ pursuant to New Zealand’s environmental policies, and in accordance with that duty. The Act provides for the use of the natural resources of New Zealand’s EEZ in a manner that is consistent with New Zealand’s international law obligations, including the UNCLOS duty to protect and preserve the marine environment.

A coastal State may claim an EEZ extending beyond its territorial waters to a distance of up to 200 nautical miles (nm) from the coastline. The EEZ is a recent innovation in the international law of the sea. In 1977 New Zealand claimed a 200 nm EEZ. The claim was made in accordance with emerging principles of customary international law, which were subsequently recognised and given clear expression in UNCLOS. The text of UNCLOS was finalised in December 1982. The Convention came into force in 1994. New Zealand became a party to UNCLOS in 1996. UNCLOS is now widely ratified, with 168 parties as at the date of judgment.

Article 56 of UNCLOS sets out the rights and duties of a coastal State that claims an EEZ. In its EEZ New Zealand has:

1. sovereign rights for the purpose of exploring and exploiting, conserving and managing the natural resources, whether living or non-living, of the waters superjacent to the seabed and of the seabed and its subsoil, and with regard to other activities for the economic exploitation and exploration of the zone, such as the production of energy from the water, currents and winds;
2. jurisdiction in relation to the protection and preservation of the marine environment, among other matters; and
3. certain other rights and duties set out in UNCLOS.

New Zealand’s duties in relation to its EEZ include the duties in relation to protection and preservation of the marine environment set out in Pt XII of UNCLOS. Article 192 of the Convention provides that States have an 'obligation to protect and preserve the marine environment'. Article 193 provides that States 'have the sovereign right to exploit their natural resources pursuant to their environmental policies and in accordance with their duty to protect and preserve the marine environment' (emphasis added by the Court). Article 194 provides that 'States shall take, individually or jointly as appropriate, all measures consistent with this Convention that are necessary to prevent, reduce and control pollution of the marine environment from any source, using for this purpose the best practicable means at their disposal and in accordance with their capabilities, and they shall endeavour to harmonize their policies in this connection.' Article 208 goes on to provide that coastal States must 'adopt laws and regulations to prevent, reduce and control pollution of the marine environment arising from or in connection with sea-bed activities subject to their jurisdiction'.

This international law framework is relevant to the interpretation of the Act. In particular, the Act can and must be interpreted to give effect to the instruments referred to in s 11: UNCLOS, the Convention on Biological Diversity of 1992, the International Convention for the Prevention of Pollution from Ships (MARPOL), the Convention on the Prevention of Marine Pollution by Dumping Wastes and Other Matter (the London Convention), and the 1996 Protocol to the London Convention. The correct interpretation approach to s 10(1)(b) of the Act, which provides that the 'purpose of this Act is ... in relation to the exclusive economic zone, the continental shelf, and the waters above the continental shelf beyond the outer limits of the exclusive economic zone, to protect the environment from pollution by regulating or prohibiting the discharge of harmful substances and the dumping or incineration of waste or other matter', is informed by these instruments, and is designed to ensure that the Act will secure compliance with New Zealand's obligations under those instruments, as s 11 confirms it was intended to do.

It is not helpful to take those international instruments into account separately, under s 59(2)(l) of the Act, in addition to looking to them to inform the interpretation of the Act. Provided the Act is properly interpreted, the result of applying the Act will be to achieve consistency with New Zealand’s obligations under those instruments. Making separate reference to those instruments via s 59(2)(l) would not add anything of substance, and would result in duplication of analysis and unnecessary complexity.

[For the unsuccessful appeal to the Supreme Court, see Trans-Tasman Resources Ltd v Taranaki-Whanganui Conservation Board [2021] NZSC 127 (CMI1600).]