In a ruling hailed by campaigners as "historic", France's top administrative court on Thursday gave the government a three-month deadline to show it is taking action to meet its commitments on climate change.
The government of France, which brokered the landmark 2015 Paris Agreement on climate change, was hauled before the Council of State by Grande-Synthe, a low-lying northern coastal town which is particularly exposed to the effects of climate change.
The Council, which rules on disputes over public policies, noted that "while France has committed itself to reducing its emissions by 40% in 2030 compared to 1990 levels, it has, in recent years, regularly exceeded the 'carbon budgets' it had set itself."
It also noted that President Emmanuel Macron's government had, in a decree in April, deferred much of the reduction efforts beyond 2020.
Despite Macron's headline 2017 promise to "make our planet great again" -- a swipe at climate denialist US President Donald Trump who vowed to "make America great again" -- France is far off track to meet its commitments under the 2015 treaty.
Before issuing a final ruling on the matter, the Council of State gave the government three months to justify "how its refusal to take additional measures is compatible with the respect of the reduction path chosen in order to achieve the targets set for 2030."
Corinne Lepage, lawyer for the town of Grande Synthe, hailed the decision as "historic".
The ruling means that "policies must be more than nice commitments on paper," she said.
In January 2019, the then Greens mayor of Grande-Synthe, Damien Careme petitioned the Council of State over what he called the government's "climate inaction".
Careme said his town of 23,000 people, which is built on land reclaimed from the sea, risked being flooded by rising sea levels.
The town's case was backed by the cities of Paris and Grenoble, as well as several environmental NGOs including Oxfam France and Greenpeace France.
The case is the latest in a series taken by climate campaigners against governments worldwide.
In an unusual move for the court, the Council of State published its decision both in English and French, reflecting the global interest in the issue.