The political battle against climate change has, so far, largely been driven by government legislation and regulation. However, a key European Court on Human Rights (ECHR) ruling this month raises a new, potentially important legal precedent in the 46 member states of the Council of Europe.

Some eight years ago, KlimaSeniorinnen (Swiss Elders for Climate Protection, a group of 2,000 Swiss women all over the age of 64) filed legal action against their government for failing to take stronger action against climate change. On April 9, the ECHR in Strasbourg (which is unrelated to the EU) surprised the Swiss Government by upholding the lawsuit — which was backed by the Greenpeace NGO — by making an approximately 300-page ruling that insufficient measures against global warming infringes the human rights of the female senior citizens involved in the case.

A sign of the importance of the case is that it was heard by the 17 judges of the so-called Grand Chamber. This is the ECHR's most prestigious chamber and it ruled 16-1 in favour of KlimaSeniorinnen.

Swiss President Viola Amherd expressed surprise at the decision. She asserted that sustainability, biodiversity and net zero are key goals for Switzerland. However, Swiss politicians are divided on the ruling. The Swiss People's Party and Centre parties are critical of it, while the Socialists and Greens support the decision.

The ruling could have major significance, in part, because it is the first time that a supranational court has ruled on climate change, finding a direct link between quality of life, health and well-being. Specifically, the judges ruled that the demographic group of older females is particularly vulnerable to climate-induced heatwaves.

The court found that the Swiss state had violated ECHR Article 8 which enshrines the "right to respect for private and family life." The right of groups of people to enjoy a "healthy environment" is a long-standing element of Article 8 case law.

The ruling sets a potentially key precedent in the 46 member states of the Council of Europe, increasing pressure on governments to step up their action. These countries include not only the 27 members of the EU, but also a wider range of nations such as Armenia, Azerbaijan, Georgia, Switzerland, Turkey, Ukraine and the United Kingdom.

To be sure, some NGOs and wider activists have had domestic legal successes, inside and outside members of the Council of Europe. For instance, a judge in Montana ruled last year that state agencies are infringing on a constitutional right to a clean environment by allowing fossil fuel development.

However, the ECHR ruling represents the first occasion an international court has upheld a climate case. So it could now influence the law across a cross-section of the diverse members of the Council of Europe. There are also ramifications for cases of a comparable nature in wider jurisdictions too, including the Inter American Court of Human Rights in Costa Rica with cases pending which relate to the human rights impacts of climate change.

While the decision may be a boon to NGOs and wider activist groups, there has already been a political backlash in some member states. One common criticism is a perception that the judges are acting as de facto legislators, rather than judges, with U.K. Government lawyer, Sudhanshu Swaroop KC, asserting that the ECHR is seeking "to legislate for a global challenge without having global jurisdiction."

The context to this statement is that the significant growth in domestic laws and regulations to address global warming is being passed at an increasing rate, especially since the 2015 Paris climate treaty was agreed upon. In a recent report by the Grantham Institute at the London School of Economics, it was revealed that there are over 800 climate change laws and policies now in places across the world, rising from 54 in 1997.

This context framed U.K. Foreign Secretary Lord David Cameron's response to the ruling earlier this month. He said, "I think it's dangerous when these courts overreach themselves, because ultimately we're going to solve climate change through political will, through legislation in this House of Lords and the House of Commons, by the actions we take as politicians, by the arguments we put to the electorate – and so I do think there's a danger of overreach."

Little surprise therefore that U.K. Prime Minister Rishi Sunak is facing growing calls from Conservatives to pull the nation out of the body. This is not only because of the climate ruling, but also because of potential ECHR legal obstacles to his Rwanda asylum policy.

The huge political challenge for Sunak is that the United Kingdom leaving the ECHR would have implications for the Good Friday Agreement underpinning the Northern Ireland peace process. It would also put the United Kingdom in a very small and undistinguished club to leave the Council of Europe, which comprises Russia and Belarus.

Taken together, the court ruling could therefore prove very significant in the years to come. However, the more that climate action shifts toward the legal arena, the greater the potential for political backlash, not just from Conservatives in the United Kingdom.

Andrew Hammond is an Associate at LSE IDEAS at the London School of Economics.