Hundreds of people across Japan will file a landmark lawsuit against the central government on Thursday (Dec 18), seeking damages for what they describe as “unconstitutional” inaction on climate change. The case, the first of its kind in the country to demand compensation from the state over climate policy failures, marks a significant escalation in climate litigation in Asia’s second-largest economy.
The lawsuit, to be filed by around 450 plaintiffs, argues that Japan’s response to the climate crisis is “grossly inadequate” and has already harmed the health, livelihoods and fundamental rights of ordinary citizens. According to a summary of the complaint obtained ahead of the filing, the plaintiffs say the government has failed to take necessary legislative and policy measures to protect their right to a peaceful life and to the enjoyment of a stable climate.
At the centre of the case are personal stories of mounting hardship as Japan experiences intensifying heatwaves, extreme weather and environmental stress. Among the plaintiffs is Kiichi Akiyama, a 57-year-old construction worker who spends much of his time labouring outdoors. He says relentless heat has dramatically slowed his work, slashing productivity and inflicting “huge losses” on his business.
“Now it takes my team nearly three times longer than estimated to finish projects,” Akiyama said. “I can barely dig with a shovel for 10 minutes without sitting down to rest.”
The physical toll, he added, is becoming increasingly dangerous. “There have been cases where people collapse out in the field, or have dropped dead after they return home,” he said, describing heat-related illnesses that are becoming more common among outdoor workers.
Japan endured its hottest summer on record this year, according to official data stretching back to 1898. The plaintiffs argue that intensifying heatwaves are no longer an abstract future risk but a present-day crisis that is already causing economic losses, damaging crops and putting lives at risk from heatstroke.
“We wouldn’t be in this terrible situation if the government had taken more initiative in implementing policies,” Akiyama said.
Legal experts say the case represents a turning point for climate litigation in Japan. While at least five climate-related lawsuits have previously been filed in Japanese courts — including cases targeting coal-fired power plants — none have sought damages directly from the state over its climate policies.
“This is the first compensation claim against the government for climate change,” said Masako Ichihara, an assistant professor at Kyoto University who has closely followed climate lawsuits in Japan. “It is bolder than previous cases because it seeks to hold the state itself accountable for climate inaction.”
The lawsuit challenges the adequacy of Japan’s current climate targets, arguing they are incompatible with the Paris Agreement’s goal of limiting global warming to 1.5 degrees Celsius above pre-industrial levels. Japan’s nationally determined contributions aim to cut greenhouse gas emissions by 60 per cent by 2035 and 73 per cent by 2040 compared with 2013 levels.
However, the plaintiffs argue these targets “fall significantly short” of the reductions outlined in the latest assessment by the UN Intergovernmental Panel on Climate Change (IPCC). They also note that the targets are not legally binding, a gap they describe as a “legislative omission” that is “unmistakably unconstitutional”.
Another plaintiff, who gave her surname as Saito, said she joined the lawsuit out of concern for her six-year-old son. Record-breaking summer temperatures, she said, are already restricting his daily life.
“Not just in pools, but playing outside generally is becoming difficult in summer,” she said. “The playground equipment is burning hot and that scares me.”
Saito noted that public swimming pools are increasingly declared off-limits during heatstroke alerts, depriving children of safe ways to cool down and play. “It feels like opportunities that should be normal for children are being taken away,” she said.
The lawsuit comes amid a growing global wave of climate litigation, as citizens and activists turn to courts to force governments to strengthen climate action. In neighbouring South Korea, young environmental activists won a landmark ruling last year when a court found large parts of the country’s climate goals unconstitutional — the first such decision in Asia.
European courts have also issued precedent-setting judgments. In 2021, Germany’s constitutional court ruled that the government’s climate targets were insufficient and violated the rights of younger generations by pushing the burden of emissions reductions into the future.
Despite these international examples, Ichihara cautioned that the chances of a clear legal victory in Japan remain slim, given the judiciary’s traditionally cautious approach to policy-heavy cases.
“From a strictly legal perspective, success is uncertain,” she said. “But if the purpose of the lawsuit is to raise public awareness and shift the national conversation, then it may succeed.”
She added that the plaintiffs’ emphasis on everyday experiences — from construction workers struggling in the heat to children unable to play outside — gives the case a “very relatable” human dimension that could resonate widely with the public.
As Japan grapples with the accelerating impacts of climate change, the lawsuit underscores growing frustration among citizens who feel the pace of government action lags far behind the scale of the crisis. Even if the courts ultimately reject the damages claim, observers say the case could exert lasting pressure on policymakers to strengthen climate commitments and translate them into binding law.
For plaintiffs like Akiyama and Saito, the lawsuit is as much about recognition as compensation. “We are already paying the price,” Akiyama said. “The government needs to be held responsible for protecting our lives and our future.”
