The public trust is an ancient doctrine, stemming from Roman law. The Institutes of Justinian state that “by natural law, these things are common property of all: air, running water, the sea, and with it the shores of the sea.” In medieval England this notion was picked up and turned into a declaration that the shores of the sea are common to all and inalienable. The concept was adopted in the United States. As early as 1821, a New Jersey court held that the state could not convey into private ownership the public lands covered by tidal waters, and that any grant purporting to do so was void. These waters are vested in the sovereign state, the court held, not for its own use, but for the use of its citizens for “passing and repassing, navigation, fishing, fowling, sustenance, and all the other uses of the water and its products...” Arnold v. Mundy, 6 N.J.L. 1 (1821).

Although the legislature may build dams, locks and bridges in the general interest of improving navigation, the court stated, “they may not consistently with the principles of the law of nature and the constitution of a well-ordered society, make a direct and absolute grant of the waters of the state, divesting all the citizens of their common right.” That, said the Chief Justice, would be a grievance “which never could be long borne by a free people.” Id at 78.
The public trust, like the ten commandments, has traditionally been phrased in terms of prohibition: “Thou shalt not abdicate the State’s control over its navigable waters.” More recently, however, this hoary common law creature, with roots in the civil laws of the Roman emperors, the English monarchs and the Spanish kings, has emerged from its long submerged home to impose new protections for the environment and new duties on governmental agencies.