The group says recommendations in the commission's major report to Government do not propose measures to tackle the problem aggressively enough. So that even if the recommendations were followed, New Zealand would exceed its carbon emissions targets and fail to meet its international obligations.
Dr Paul Winton, from the 1Point5 Project, said the legal action is "crucial", as climate change is a looming threat.
"This is a really important piece of legal action, because it seeks to bring the thinking from the Climate Change Commission in line with the science of climate change, which the advice that was submitted in May does not unfortunately do."
Winton said the commission's advice was also inconsistent with the purpose of the Zero Carbon Act.
And he supported the legal action's aim to bring the commission's thinking in line with the science of climate change.