This is a guest post by Chris Wood , adapted from his brand new book, Down the Drain: How We Are Failing to Protect Our Water Resources .
What we have here is a system failure.
It’s not just that our profligate burning of fossil fuels is winding up the planet’s thermostat. Nor that our rampant over-consumption of goods and overflowing wastes are exhausting its resources. Nor even that market-driven media and money-fueled politics are obscuring these vital truths.
The more intractable problem is that these threats and many more besides are the permissible, even inevitable, products of underlying laws and customs that constitute our socio-political operating system.
What this implies is that we need not only a host of new practical ideas—new technologies, new materials—but also fundamental changes in laws that enable and even in some instances compel behaviors that are leading us daily closer to climageddon.
We need, that is, an upgrade to our legal operating system. And just like an upgrade to the OS running on your laptop, we need it to be ‘backward compatible’: able to work smoothly with as much as possible of our existing structures of law and legal practice.
With origins that can be traced back through numerous cultures to the very earliest legal codes, and a continuing role in modern jurisprudence, this may be just the upgrade we’ve been waiting for. In the United States it’s called the ‘public trust’ doctrine. Elsewhere it’s known as the ‘fiduciary duty’ of government.
The two terms are really just two sides of the same coin, the reciprocal ideas that some natural assets—historically water; today the atmosphere—transcend private ownership and belong to all citizens, and that the sovereign state bears a duty to preserve them.
Historically, these ideas are found in Roman laws that protected the public’s right of access to the seashore and banks of rivers. They appeared in North America with the earliest expressions of colonial law: the French and Spanish civil codes. They appear again in the Ordinances that guided 17th century Massachusetts and, a century or so later, the proto-territories of Michigan and Montana.
Confirmed in a landmark U.S. Supreme Court decision in 1892, the traditional reading of the doctrine holds that waterways—essential to life and trade, but also susceptible to injury from every user—are an asset belonging in common to all citizens and managed on their behalf by the state: hence, a ‘public trust’.
Correspondingly, the managers of that trust, legislatures and state agents, bear a fiduciary duty to preserve that asset for the benefit of present and future generations, just as those who manage a private trust fund bear a duty to protect its capital for the trust’s beneficiaries.
Over the last century, states have steadily expanded the scope of this idea. California has extended the “affirmative duty” of the state to the protection of scenic views and wildlife habitat. Louisiana includes historic and aesthetic qualities of the environment in its determination of the public trust. Montana includes “atmospheric waters.” Courts in Utah have suggested the public trust extends to the “ecological integrity” of public landscapes.
Internationally, a recent review  by a professor and a PhD candidate at the Lewis and Clark Law School found examples of the public trust at work in a dozen countries, from Brazil to Uganda. In a particularly telling series of decisions, the Filipino Supreme Court has held that the public trust exists as a matter of natural law independent of statute or constitutional protections. As it stated in one case, “the right to a balanced and healthful ecology need not even be written in the Constitution, for it is assumed… to exist from the inception of mankind.” Significantly, the same court maintained that even in “the absence of a categorical legal provision, [public agencies] cannot escape their obligation to future generations” to preserve a secure environment.
Four dozen other countries, mainly in Europe and western Asia, have adopted the Aarhus Convention , premised on the idea that “every person has the right to live in an environment adequate to his or her health and well-being, and the duty… to protect and improve the environment for the benefit of present and future generations.” Signatory nations undertake to provide their citizens with periodic reports on the condition of their environment—the equivalent of quarterly reports on the principle held in a financial trust. Moreover, when a citizen believes that a state has failed in this obligation, he or she may take that state to court.
Most recently, pioneering legal scholars and activists have invoked the public trust doctrine to demand  that governments mitigate impending disruption to the climate.
That effort has had only fitful success, and conservative courts from Canada to Texas have sharply restricted the scope of suits based on ideas of public trust or state fiduciary duty.
But that may be changing. The same factors that made water an obvious candidate for state protection in colonial America—its ubiquity, mobility, necessity to life and susceptibility to injury from private actions—apply with even greater force to the atmosphere. Moreover, it is becoming evident that the natural assets which form the undisputed core of the public trust—waterways, lakes and seacoasts—are at risk from atmospheric warming that is redistributing rainfall, amplifying floods and intensifying droughts in every region. So too are the wildlife and ecosystems brought into the scope of the public trust over the last century.
In this century we are witnessing a re-examination of the role of the state on multiple fronts, from its responsibility for the economic welfare of citizens to its ability to constrain the activities of global corporations. Still, a handful of duties remain synonymous with sovereignty: maintaining civil order, protecting the integrity of the state (national security) and a sound currency.
In Down the Drain: How We Are Failing to Protect Our Water Resources , my co-author Ralph Pentland and I argue that none of these sovereign obligations can be met unless states also accept a fourth duty: protection of the natural security embodied by a resiliently human habitat and the stable climate on which it depends.
Where this obligation has been codified explicityly into statute law (in places like Michigan, South Africa and the Aarhus group), three key elements have emerged: an inalienable public trust interest in a healthy natural environment; a reciprocal affirmative fiduciary duty on the part of the state to protect that interest; and the right of ordinary citizens to seek redress from independent courts when governments fail in that duty.
States, largely dominated by economic interests with other priorities, will resist accepting this obligation. Our survival depends on their doing so however, because then all those other public choices—from over-exploitation of resources to the release of climate-altering gasses—must be made in a new light, judged by whether they do or do not protect our common interest in a livable future.
No national priority can possibly be greater than that. Which is why the ancient concept of the ‘public trust’ may just be the most important legal and political idea of the present century.
Chris Wood is a Canadian writer and journalist, based currently in Mexico, and the author of several books about climate, sustainability and international law.