The Public Trust Doctrine has its origins in civil law. Under civil law, the air, the rivers, the ocean, and therefore the seashore were incapable of personal ownership; they were dedicated to the utilization of the general public. It could also be used by the courts as a tool to protect the environment from many kinds of degradation. In some countries, the doctrine has formed the idea of environmental policy legislation, allowing private rights of action by citizens for violations by the state (directly or indirectly) of the public trust.
In National Audubon Society v. Superior Court of Alpine County, it was held that the State has an affirmative duty to take the public trust into account in the planning and allocation of water resources, and to guard public trust uses whenever feasible. Just as the history of this State shows that appropriation could also be necessary for efficient use of water despite unavoidable harm to public trust values, it demonstrates that an appropriative water rights system administered inconsiderately of the general public trust may cause unnecessary and unjustified harm to trust interests.
Hon’ble Supreme Court of India has held the doctrine of public trust as one of the parts of the Indian jurisprudence on sustainable development within the case of M.C. Mehta v. Kamal Nath, it was held that the source of modern public trust law is found in a concept that received much attention in Roman and English law – the nature of property rights in rivers, the sea, and also the seashore. The Public Trust Doctrine primarily rests on the principle that certain resources like air, sea, waters, and thus the forests have such a big importance to the people as a whole that it might be wholly unjustified to form them a subject of personal ownership. The said resources being a present of nature, they ought to be made freely available to everyone regardless of their status in life. The doctrine encourages the government to protect the resources for the enjoyment of the general public rather than to permit their use for private ownership or commercial purposes. These resources meant for public use can’t be converted into private ownership.
The principle of intergenerational equity-
Intergenerational equity simply implies an obligation of the present generation towards future generations. A trust in which the present generations of human beings are obliged to take care of the natural resources and ecology so that all future generations shall also have an equal chance to enjoy mother nature and the right to life.
The present generation features a right to use and luxuriate in the resources of the planet but is under an obligation to take under consideration the future impact of its activities and to sustain the resource base and therefore the global environment for the advantage of future generations of humankind. “Development that meets the requirements of this without compromising the power of future generations to satisfy their own needs”