We have crossed a defining threshold, both in environmental law and in ecology. In law, we see a new era of environmental constitutionalism, and not at all unrelatedly, we find ourselves in a new ecological era that is marked by colossal human destruction of the very systems sustaining all life on Earth. Bill McKibben says it is as if we have destroyed our planet that sustained us and are now on a different planet altogether. And as the years pass, it will feel more and more that way. Our climate system is so disrupted by the greenhouse gases that have accumulated in the atmosphere that we now face a clear existential threat to humanity and society. As a Ninth Circuit Court of Appeals panel put it, we are nearing the “eve of destruction.”

There have been nearly 3,000 “climate litigation” cases. The U.S. is responsible for nearly two out of three of these. Yet neither Congress, the U.S. Constitution nor common law have exhibited much if any capacity for addressing or redressing climate change. International and regional instruments as well offer potential but little progress.

Subnational constitutions in America can help to fill the breach. There is a growing cadre of ‘climate rights’ cases that arise under state constitutions. For example, a state court in Montana recently ruled that a state law prohibiting consideration of climate impacts violates that state’s constitutionally enshrined environmental right, the Hawai’i Supreme Court has issued a series of decisions recognizing climate rights, and other state constitutions recognize rights that can arguably reach climate change. A wave of subnational climate rights cases is underway.

Much has been written about climate law and litigation yet little about subnational climate rights. This paper argues that the future engagement of climate rights in the United States is likely to occur at the subnational level based on either explicit rights to a healthy environment or on implicit implications of socioeconomic rights, such as to life, health and dignity. Part I asserts that the limits of international, regional and domestic national law create an opportunity for consideration of impactful subnational climate rights litigation in the U.S. Part II examines what I call “Environmental Climate Rights,” that is, climate rights based on constitutionally instantiated environmental rights, including at the subnational levels in Pennsylvania, Montana and Hawai’i, and sees promising if limited progress. Part III explores what I call “Socioeconomic Climate Rights,” that is, climate rights based on other constitutionally incorporated human rights, such as to life, health and dignity, and argues that there is untapped potential here. Part IV argues in favor of further exploration of subnational climate rights in the U.S.

Constitutional environmental rights are in vogue. In the United States and across the world, plaintiffs frequently claim that their governments, in failing to adopt and implement sufficiently ambitious policies, have violated constitutionally-protected rights to an environment of a certain quality. Such claims have garnered considerable success in many jurisdictions. And in the United States, the first such successful claim was recently accepted by a state trial court in Montana. Environmental rights are imagined as a valuable weapon to be wielded against recalcitrant governments.

Environmental rights are having a moment. Though only eight states and territories have expressed environmental rights provisions in their constitutions, a trickle of positive developments has seemingly turned into a stream. Supreme courts in Hawaiʻi and Pennsylvania gave some force to their states’ rights provisions beginning in the 2010s—and the scope of protections guaranteed by each right continues to be fine-tuned by litigation. In 2021, New York voters added an environmental rights provision to their state’s constitution—the first such addition of the twenty-first century. More states may well add similar amendments to their constitutions.