The European Court of Human Rights ordered the governments of 33 European countries Monday to respond to a milestone climate change lawsuit brought by six young Portuguese climate activists.

The court ordered all 33 governments, including the EU27, plus Ukraine, Turkey, the UK, Switzerland, Russia and Norway, to respond to the lawsuit by February 23. According to a press release from the plaintiffs’ counsel, “the vast majority of cases filed with [the court] fail to reach this stage [and] this decision marks a major step towards a potential landmark judgment on climate change.” Additionally, the court announced it would prioritize the case on the basis of “the importance and urgency of the issues raised.”

The plaintiffs—two young adults and four children—argue that European governments need to set more aggressive climate goals to protect future generations from the physical and mental impacts of climate change. They also argue that countries must work more quickly to reduce greenhouse gas emissions and increase climate stabilization efforts. The plaintiffs, ranging from 8 to 21 years old, all reside in Portugal, where the effects of climate change are becoming more and more evident. This year, the country recorded its hottest July in 90 years.

After raising enough support through international crowdfunding efforts, the plaintiffs filed the lawsuit in September with the Strasbourg-based court. The group seeks a legally binding decision “requiring governments in Europe to take the urgent action needed to stop the climate crisis.” Beyond just domestic emissions cuts, the plaintiffs also hope the court will order the countries to “tackle overseas contributions to climate change, including those of [the countries’] multinational enterprises.”

Despite its recent filing date, the case itself has been in the works for several years. Four of the plaintiffs live in Leiria, one of the worst-hit areas during the 2017 forest fires that ripped through Portugal, killing more than 120 people. The crowdfunding initiative began following the fires. The other two plaintiffs reside in Lisbon, where heat records shattered in 2018 at 44 C (111 F) degrees.

The case is the latest in a string of youth-led climate change lawsuits around the world. In July a 23-year-old law student launched a suit to hold the Australian government accountable for climate change risks, and another eight students did so in September.