The Public Trust Doctrine
“By the law of nature these things are common to mankind – the air, running water, the sea, and consequently the shores of the sea.” —Emperor Justinian, 530 AD
To better understand what the doctrine obligates the state to do and what implementation of the doctrine looks like, we must understand the doctrine’s history and examine the role the public trust doctrine played in its most prominent case, the Mono Lake decision.
Since then, the doctrine has evolved to provide stronger environmental protection. The law was incorporated into English Common Law, and passed down to the US through prominent court cases at the Federal (Illinois Central) and California state level. Justinian’s version of the public trust doctrine ensured that the public had access to water and tide resources, and protected the resources from encroachment by private enterprise. However, in the 1970s, the doctrine was used by environmental advocates for protection of environmental resources in litigation, which expanded the scope of the public trust doctrine. The best-known example is the Mono Lake decision.
In 1979, the Mono Lake Committee (MLC) brought suit against the Los Angeles Department of Water and Power (DWP) for violating the public trust doctrine in its diversion of water from the streams feeding into Mono Lake. DWP Diversions caused the lake level to recede to ecologically dangerous levels, threatening alkali flies, bird populations, and tufa structures. The MLC argued that the state was obligated to protect them because “the shores, bed and waters of Mono Lake are protected by a public trust."
In 1983, the court issued a decisive ruling in National Audubon Society v. Superior Court that clarified the role of the public trust doctrine in California water law. The State Water Resources Control Board followed up with its own water rights decision to implement the court's will. Though the decision essentially obligated DWP to reduce diversions to a level that would protect public trust resources, the court’s decision did not place the public trust doctrine above other water laws in California. Instead, the courts decided that the state should “attempt, so far as feasible, to avoid or minimize any harm to those [public trust] interests”.
Content prepared by C-WIN Intern Ariel Frink