Thomson v The Minister for Climate Change Issues

Sarah Thomson, a law student concerned about climate change, brought judicial review proceedings challenging the Government's response to climate change. The proceeding challenged two decisions made by the Minister for Climate Change Issues concerning greenhouse gas emission reduction targets: (1) a 2050 target (50% reduction from 1990 levels by 2050) set under s 224 of the Climate Change Response Act 2002 and gazetted in 2011, and (2) a 2030 target (30% reduction from 2005 levels by 2030) communicated as New Zealand's Nationally Determined Contribution (NDC) under the Paris Agreement in 2015-2016. The plaintiff argued the Minister failed to review the 2050 target after the AR5 IPCC report was published in 2013-2014, and that the NDC decision failed to take into account relevant considerations and was irrational/unreasonable. Both parties accepted the scientific consensus that climate change presents significant risks requiring serious and prompt global action.

• Whether s 225 of the Climate Change Response Act 2002 required the Minister to review the 2050 target following publication of the AR5 IPCC report
• Whether the Minister was required to exercise her discretionary power under s 224 to review the 2050 target following the AR5
• Whether the NDC decision setting the 2030 target was amenable to judicial review
• Whether the Minister failed to take into account mandatory relevant considerations when making the NDC decision (costs of climate change inaction, impacts on Tokelau and developing countries, inadequacy of combined global INDCs)
• Whether the NDC decision was irrational/unreasonable

The application for judicial review was dismissed. The Court declined to make declarations or orders on any of the causes of action. Costs to lie where they fall (preliminary view).

The binding legal principles established are: (1) Under s 224(2) of the Climate Change Response Act 2002, the publication of a new IPCC Assessment Report is an implicit mandatory relevant consideration requiring the Minister to consider whether the new report materially alters the information against which an existing gazetted target was set, and if so, to review that target. (2) Government decisions on climate change targets and Nationally Determined Contributions under the Paris Agreement are amenable to judicial review on traditional grounds (failure to consider mandatory relevant considerations, irrationality/unreasonableness), notwithstanding that they involve international obligations not incorporated into domestic law and require balancing of competing policy factors. (3) The justiciability of government action depends on the particular ground of review rather than the subject matter being a "no-go area". (4) Sections 224 and 225 of the Climate Change Response Act must be interpreted consistently with New Zealand's international obligations under the UN Framework Convention on Climate Change, the Kyoto Protocol and the Paris Agreement. (5) The impact on Tokelauans is a mandatory relevant consideration when New Zealand considers its climate change responses, given Tokelau's status as part of New Zealand and its vulnerability to climate change.

Mallon J made several non-binding observations: (1) There may have been better ways for the Minister to assess costs of climate action and inaction through economic modelling, which a new Minister may pursue. (2) The AR5 represents a "conservative" consensus according to some experts, though government reliance on it is acting in accordance with the bulk of evidence. (3) Professor Frame's analysis showed New Zealand's 2030 target was somewhat less ambitious than its 2050 target and the EU's target, which may increase costs of future emissions reductions, but this does not make it inconsistent with the Paris Agreement temperature goal. (4) The new Government's announced intention to set a new 2050 target (zero carbon by 2050) and potential changes to the ETS indicate the democratic process provides accountability for climate policy decisions. (5) The Court noted the importance of the issues at stake given climate change presents "significant risks" requiring "serious and prompt global action" and affects all inhabitants of the planet. (6) The international framework envisages review and demonstrated progression by developed countries, and New Zealand remains free to review its targets as appropriate regardless of international requirements.

This is the leading New Zealand decision on justiciability of government climate change policy decisions. It establishes that: (1) climate change decisions are amenable to judicial review despite involving international obligations and policy balancing; (2) IPCC reports are implicit mandatory relevant considerations when reviewing emission reduction targets under the Climate Change Response Act 2002; (3) courts have a constitutional role in scrutinizing climate change decisions on traditional judicial review grounds while respecting separation of powers; (4) impacts on Tokelau and developing countries are mandatory relevant considerations for New Zealand's climate decisions; (5) the Paris Agreement framework allows nationally determined contributions with flexibility in how targets are set and met. The case illustrates judicial engagement with complex climate science (particularly AR5 findings) and the constitutional limits of judicial intervention in policy-laden executive decisions involving economic, social and environmental factors. It reflects the global trend of increased judicial scrutiny of government climate action, while stopping short of ordering specific emission reduction targets.