A 26-year-old Hamilton law student is suing the Government over what she says is New Zealand's inaction on climate change.
Sarah Thomson's lawsuit has gone all the way to the Wellington High Court, which is set to hear the case over the next three days.
Ms Thomson is seeking a judicial review over the decision by the Government to not reset emissions reduction goals after signing the global Paris Climate Agreement.
Her lawyer Davey Salmon said with no Upper House of Parliament, seeking a judicial review is the only way the Government's decision can be properly scrutinised.
Mr Salmon said the case is not a debate about science and both sides agree climate change is happening because of human activity.
Instead, he says at the heart of the case is the Government's idea New Zealand could do less because as a country we are relatively small.
"That is not how you solve a common problem," Mr Salmon said.
"When the ship is sinking it doesn't matter how big you are, everyone bails."
Mr Salmon said there are "evident logical fallacies" in the Government's decision not to review emissions targets.
One of the targets to be scrutinised is New Zealand's contribution under the Paris Agreement, which commits New Zealand to reducing greenhouse gas emissions by 11 percent below 1990 levels by 2030.
The lawsuit will ask Climate Change Issues Minister Paula Bennett to justify the way in which the Government's climate targets have been set.
In her preliminary Statement of Defence, Ms Bennett has denied that the Government needs to set a target that strengthens the global response to climate change to hold warming to below 2degC.
When the judicial review proceedings were initially filed, then-Prime Minister John Key dismissed the legal action as "a joke".
"If we're getting sued, I hate to think what's going to happen to the United States and Australia and other countries because their climate change targets are lower than ours," he said.