The Supreme Court of the Netherlands in The Hague on Friday delivered what may be the most unequivocal legal statement so far that governments are responsible for acting to address climate change.
In a closely-watched case that could have wide ramifications for litigation worldwide, the court ruled that the Dutch government must reduce emissions by at least 25% by the end of 2020 compared to 1990 levels, going beyond the EU-wide objective of 20%.
The ruling denied the Dutch government’s appeal of an earlier ruling in favor of the Urgenda Foundation, an environmental group that first filed the case in 2013 on behalf of a group of Dutch citizens who wanted the government to move faster to reduce emissions. The government has argued that a legal obligation to meet a specific target would limit its flexibility in determining how to reduce emissions.
The Supreme Court said on Friday that it based its judgement on the UN Climate Convention and the obligations of the state under the European Convention on Human Rights.
“There is a great deal of consensus in science and the international community about the urgent need to reduce greenhouse gas emissions by at least 25 percent by developed countries by the end of 2020,” the court said in its summary, translated from the Dutch. “[The Netherlands] has not explained why a lower reduction can be considered justified and can still lead in time to the final goal accepted by the State.”
In a brief summary read in English, the judge presiding over the court noted that European Human Rights Convention Articles 2 and 8—the right to life and the right to respect for private and family life—indicate that action on climate change falls under the umbrella of human rights protection.
“These articles entail the positive obligation for the Dutch state to take reasonable and appropriate measures to protect the residents of the Netherlands from the serious risk of a dangerous climate change, that would threaten the lives and wellbeing of many people in the Netherlands,” he said.
That obligation to apply the provisions of the Convention trumped the state’s argument that politicians—not the courts—are responsible for determining emissions reductions, the Court said.
On Friday, Dennis van Berkel, the counsel for Urgenda, said the ruling was “a really special moment.”
“This is an incredibly strong judgment and this is an incredibly strong signal both in the Netherlands and outside,” he said. After the unsuccessful negotiations on collective climate action at this month’s COP25 in Madrid, he said this ruling proved “there is hope” that something can be done about climate change.
In a statement to the president of the Netherlands’ legislative lower house on Friday, Eric Wiebes, the minister of economic affairs and climate policy, said that “given the broad significance” of the ruling, the government wished to study it carefully and issue a response in the second half of January. Wiebes noted that the government has already started putting in place policies to implement the target set by the judgement.
In a statement in November after the earlier appellate ruling, the government argued that the court’s judgement limited its freedom of choice to establish policy on the scope of emissions reductions.
“This could have significant consequences for governments’ freedom to make climate policy and in other areas,” the government said. The statement noted that the state was still committed to lowering emissions by 25% by 2020.
In 2018, emissions in the country were down 14.5% from 1990 levels, according to Statistics Netherlands.
The Urgenda case has gotten the furthest of all international litigation regarding climate change, according to Michael Gerrard, founder and director of the Sabin Center for Climate Change Law at Columbia University. Together with the law firm Arnold & Porter, the Center runs a database to track climate change litigation both internationally and in the U.S.
“There have been 1,442 climate change lawsuits worldwide. This is the strongest decision ever,” said Gerrard. “The Dutch Supreme Court has upheld the first court order anywhere directing a country to slash its greenhouse gas emissions. This decision may inspire even more cases in other countries.”
That was a sentiment that was echoed by Markus Gehring, an expert in sustainable development law at the University of Cambridge.
“The beauty is you only need one successful case,” he said. “There is [now] an expectation that climate litigation will multiply.”
The overall success of climate change litigation has so far been mixed, he said, with some cases focusing on government responsibility and others focusing on major emitters, including energy companies.
Gehring predicted that courts’ reluctance to rule on obligations to reduce emissions was likely to further wane, as the science on the impact and cause of climate change has become more unequivocal. That legal threat, in turn, could motivate governments to move more quickly on climate policy.
“The only way to prevent a global wave of climate litigation is to make progress on the government side,” he said.
This story was updated to reflect the response of the Dutch government following the ruling.
More must-read stories from Fortune:
—2020 Crystal Ball: Predictions for the economy, politics, technology, and more
—Climate change is hitting the insurance industry hard: How Swiss Re is adapting
—Russia and China have built a new gas pipeline that has everything—except profit
—Innovative tech offers a solution to aircraft pollution
—The Future 50 sustainability all stars
Subscribe to The Loop, a weekly look at the revolutions in energy, tech, and sustainability.