An ancient legal principle has become a key strategy of American children seeking to reduce the effects of climate change in the 21st century. A defeat at the U.S. Supreme Court in March 2025 has not stopped the effort, which has several legal actions continuing in the courts.
The legal basis for these cases is called the “public trust doctrine,” the principle that certain natural resources – historically, navigable waters such as lakes, rivers and streams and the lands under them – must be maintained in government ownership and held in trust for present and future generations of the public.
Although the origins of the doctrine remain in some dispute, most scholars cite its first mention in ancient Roman law. Over the centuries the principle made its way to England and later to the United States.
For the past decade, a nonprofit called Our Children’s Trust has argued for a 21st-century interpretation of the public trust doctrine to support lawsuits against state and federal agencies and officials, seeking to force them to take specific actions to fight climate change. Our Children’s Trust has focused on children, saying they are particularly vulnerable to the effects of climate change because their futures, which the public trust doctrine protects, will be lived in an unsafe and unhealthy climate unless governments take action. Children around the world have filed similar lawsuits against their governments on alternate legal grounds, including claims of constitutional and human rights violations.
Initial uses of the public trust doctrine in the US
The U.S. Supreme Court first endorsed the public trust doctrine in 1892, when it ruled that the doctrine prevented the Illinois legislature from selling virtually the entire Chicago harbor in Lake Michigan to a private railroad company. In the 20th century, state courts have ruled that the doctrine bars states and local governments from selling off lakefront property or harbors to private owners and protects public access to beaches, lakes and oceans.
The public trust doctrine had little to do with environmental protection until the 1970s, however, after law professor Joseph Sax wrote an influential article arguing that the doctrine could form the basis for lawsuits to protect water and other natural resources from pollution, destruction and other threats.
Over the past five decades, some states’ courts have expanded the public trust doctrine’s application beyond access to water-based resources, ruling it can also require governments to protect parks and wildlife from development. And Montana, Minnesota and several other states followed Sax’s recommendation to pass laws or amend their state constitutions to impose broader obligations on states to protect natural resources.
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A new approach
In 2011, Our Children’s Trust argued for the first time that governments had a legal obligation to protect the atmosphere as a public trust resource. The group filed lawsuits in all 50 states on behalf of children. Most state courts dismissed the lawsuits quickly, holding that there were no court decisions in their states that supported extending the public trust doctrine to claims involving the climate or the atmosphere.
In 2015 the group filed a similar lawsuit in federal court in Oregon, this time against the federal government. That lawsuit, Juliana v. United States, alleged that the federal government’s inaction to address climate change violated the public trust doctrine as well as the 21 young plaintiffs’ rights to life, liberty and property under the U.S. Constitution.
The plaintiffs asked the court to order the federal government to prepare an inventory of U.S. carbon dioxide emissions and to implement a national plan to phase out fossil fuels to “stabilize the climate system and protect the vital resources on which Plaintiffs now and in the future will depend.”
The federal lawsuit survived an early effort from the government to dismiss the case but never reached a full trial. In 2016 an Oregon federal judge ruled that the U.S. government had an obligation to protect the climate under both the public trust doctrine and the U.S. Constitution. However, this ruling was reversed on appeal. After years of back-and-forth in the court system, the U.S. Supreme Court upheld the case’s dismissal in March 2025.
An updated strategy
Since the initial wave of litigation, Our Children’s Trust has continued to file lawsuits to force governments to address climate change. These newer ones are more narrowly tailored to state-specific constitutional and statutory provisions that protect environmental and public trust resources. And, so far, they have been more successful.
In a 2020 Montana lawsuit, for example, the plaintiffs relied on a 1972 amendment to the state constitution declaring that the state and every person “shall maintain and improve a clean and healthful environment in Montana for present and future generations” and that the legislature shall “provide adequate remedies to prevent unreasonable depletion and degradation of natural resources.” Montana Supreme Court decisions prior to the 2020 lawsuit had held that the framers of the 1972 amendment had intended it to contain “the strongest environmental protection provision found in any state constitution.”
Relying on these court decisions, the Montana plaintiffs argued that a state law preventing state agencies from considering the effects of greenhouse gases in issuing permit applications for projects such as power plants or mines violated the state constitution.
The plaintiffs won at trial, and in a landmark opinion in 2024 the Montana Supreme Court upheld the trial court’s finding that greenhouse gases were harmful to the state’s “climate, rivers, lakes, groundwater, atmospheric waters, forests, glaciers, fish, wildlife, air quality, and ecosystem.” The court similarly found that “a stable climate system … is clearly within the object and true principles” of the state’s constitution.
Children in Hawaii filed a similar lawsuit in 2022 against the state Department of Transportation, alleging that its failure to reduce transportation emissions in the state violated the state public trust doctrine and the state’s constitution. The lawsuit relied on Hawaii courts’ previous rulings that the state’s public trust doctrine and state constitution broadly protect natural resources for present and future generations. In 2024, days before trial was to begin, the parties reached a landmark settlement in which the state agreed to take concrete actions to significantly reduce greenhouse gas emissions from the transportation sector.
The road ahead
Looking back, it was perhaps not surprising that a one-size-fits-all nationwide legal strategy based on a doctrine that varies widely state by state would face long odds. But the public trust doctrine itself has been historically incremental, expanding and contracting as society and the needs of its citizens change over time. And Our Children’s Trust has several cases still pending, including in Alaska and Utah state courts, and in a federal court in California.
The campaign’s successes broke new legal ground: Montana courts held the first trial in the United States that examined evidence of the effects of climate change and states’ obligations to address them. The Hawaii settlement set concrete benchmarks and included provisions for continued feedback on state policies by the youth plaintiffs.
More broadly, Our Children’s Trust’s campaign demonstrates that a combination of legal advocacy and nationwide publicity over the plight of young people in a rapidly changing climate have the potential to result in real change, both in the law and in public perception of the importance of addressing climate change.