Europe’s top human rights court said in a landmark ruling on Tuesday that the Swiss government had violated its citizens’ human rights by not doing enough to stop climate change.

But the court rejected climate-related cases brought by the former mayor of a coastal town in France and a group of young people in Portugal as inadmissible.

The cases, the first of their kind to be heard at the court, the European Court of Human Rights in Strasbourg, France, are part of a broader movement of climate-related lawsuits that aim to use human rights law to push governments to act against global warming.

The rulings focused on three cases, filed by members of the public in France, Portugal and Switzerland who argued that their governments, by not doing enough to mitigate climate change, were violating the citizens’ rights under the European Convention on Human Rights.

The court “has actually said that by not meeting its targets on climate, Switzerland has violated the rights of the European human rights convention,” said Annalisa Savaresi, a professor of environmental law at University of Stirling in Scotland.

National courts would be watching the ruling closely, she said. “This is huge.”

Older women vs. Switzerland

A group of Swiss women age 64 and up — known as the KlimaSeniorinnen, or Senior Women for Climate Protection — argued in their lawsuit that the Swiss government’s failure to reduce greenhouse emissions enough to stop global warming has violated their rights to life and autonomy.

With heat waves sweeping Switzerland in recent summers and older women particularly vulnerable to heat-related illnesses, the litigants said that the government had not acted enough to protect their final decades. The Swiss government argues that human rights law does not apply to climate change, and that addressing it should be a political process.

A mayor vs. France

A second case focuses on a complaint by Damien Carême, a former mayor of Grande-Synthe, a town on the coast of the English Channel, that France has taken insufficient steps to prevent global warming, thus endangering the town.

Mr. Carême, who was the town’s mayor from 2001 to 2019 and is now a member of the European Parliament for France’s Green party, argued that this failure violates the right to life, which is enshrined in European law. The town of Grande-Synthe is expected to be particularly affected as it faces an increased flooding risk in the coming decades because of climate change.

Portuguese youth vs. 33 countries

Six Portuguese young people born from 1999 to 2012 argued in a third case that the current and future effects of climate change — including heat waves, wildfires and the smoke from those blazes — are affecting their lives, well-being and mental health. They blamed 33 Paris Climate Agreement signatory countries in the region for failing to comply with their commitments to reduce greenhouse emissions.