Public trust doctrine
|Pollution control and remediation|
|Resource conservation and management|
|Planning, land use, and infrastructure|
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The ancient laws of the Roman Emperor Justinian held that the seashore (defined as waters affected by the ebb and flow of the tides) not appropriated for private use was open to all. This principle became the law in England as well. In the Magna Carta in England centuries later public rights were further strengthened at the insistence of the nobles that fishing weirs which obstructed free navigation be removed from rivers.
These rights were further strengthened by later laws in England and subsequently became part of the common law of the United States as established in Illinois Central Railroad v. Illinois, 146 U.S. 387 (1892). In that case the Illinois Legislature had granted an enormous portion of the Chicago harbor to the Illinois Central Railroad. A subsequent legislature sought to revoke the grant, claiming that original grant should not have been permitted in the first place. The court held that common law public trust doctrine prevented the government from alienating the public right to the lands under navigable waters (except in the case of very small portions of land which would have no effect on free access or navigation).
The public trust applies to both waters influenced by the tides and waters that are navigable in fact. The public trust also applies to the natural resources (mineral or animal) contained in the soil and water over those public trust lands.
The doctrine is most often invoked in connection with access to the seashore. In the United States, the law differs among the fifty states but in general limits the rights of ocean front property below the mean high tide line. Massachusetts and Maine (which share a common legal heritage) allow private ownership as far as the mean low water line but allow for public rights to fishing, fowling and navigation (with the necessary permits). These two states are the most restrictive of public rights and represent the exception. Most states allow free access to the intertidal zone for walking, swimming, sunbathing, etc. This does not always include the right to cross private land to reach the shore but prevents private owners from excluding the public below the mean high tide line. This line is calculated as the average high tide line of a 14.1 year cycle which means in practical terms that neither property owners nor the public are likely to be able to identify its precise location. On tidal waters the burden of proof therefore falls to the property owner as it would be trespassing for the public to willfully cross above the mean high tide line but not to miscalculate its location. On smaller creeks and streams the burden of proof falls on the party claiming the navigable servitude, Harrison v. Fite, 148 F. 781 (1906) .
Natural resources 
The doctrine has also been used to provide public access across and provide for continued public interest in those areas where land beneath tidally influenced waters has been filled. In some cases, the uses of that land have been limited (to transportation, for instance) and in others, there has been provision for public access across them.
The doctrine has been employed to assert public interest in oil resources discovered on tidally influenced lands (Mississippi, California) and has also been used to prevent the private ownership of fish stocks and crustacean beds.
In most states in the United States, lakes and navigable-in-fact streams are maintained for drinking and recreation purposes under a public-trust doctrine.
The public trust doctrine at Mono Lake, California 
Mono Lake, an ancient saline lake in California's Eastern Sierra, was long threatened by the diversion of its tributary streams south to Los Angeles, thereby lowering the water levels. In 1983 the California Supreme Court ruled in National Audubon Society v. Superior Court that Mono Lake is a public trust resource of the state of California. This was an important victory for the Mono Lake Committee, the National Audubon Society, and other advocates for the lake. Expanding the ancient doctrine to include recreational and aesthetic values and the importance of the lake to wildlife, the Court decreed that Mono Lake has "public trust values" that the state has an obligation to maintain. In the words of the Court, "The public trust...is an affirmation of the duty of the state to protect the people's common heritage of streams, lakes, marshlands and tidelands."
The Court ruled that the water rights of Los Angeles and the public trust values of Mono Lake had to be more fairly balanced, and that the water rights of the City of Los Angeles would have to be revisited to assure proper public trust protections. The Mono Lake Committee has been working since 1978 to achieve this balance.
See also 
Further reading 
- Sax, Joseph L. (1970). "The Public Trust Doctrine in Natural Resource Law: Effective Judicial Intervention". Michigan Law Review (The Michigan Law Review Association) 68 (3): 471–566. doi:10.2307/1287556. JSTOR 1287556.
- Slade, David C. (2008). The Public Trust Doctrine in Motion. PTDIM, LLC. ISBN 978-0-615-24111-1.
- Velozo de Melo Bento, Lucas (November 14, 2009). "Searching for Intergenerational Green Solutions: The Relevance of the Public Trust Doctrine to Environmental Preservation". Common Law Review (11): 7–13.
- Michael Seth Benn, Towards Environmental Entrepreneurship: Restoring the Public Trust Doctrine in New York, 155 University of Pennsylvania Law Review 203 (2006).
- Patrick S. Ryan, Application of the Public-Trust Doctrine and Principles of Natural Resource Management to Electromagnetic Spectrum. Michigan Telecommunications and Technology Law Review, Vol. 10, No. 2, 2004.
- James L. Huffman, Ph.D., "Fish Out of Water: The Public Trust Doctrine in a Constitutional Democracy " Issues in Legal Scholarship, Joseph Sax and the Public Trust (2003): Article 6.
- "Restoring The Trust: Water Resources & The Public Trust Doctrine, A Manual For Advocates" by the Center for Progressive Reform, September 2009
- Mono Lake Committee website