Question

Passage:
The legal concept known as the Public Trust Doctrine (PTD) is a foundational principle of environmental and property law, postulating that certain natural resources are preserved for public use, and that the government owns them not as a proprietor, but as a trustee for the public. The doctrine’s conceptual origins are typically traced to the Institutes of Justinian—a compilation of Roman law issued in 533 CE—which declared that by the law of nature, certain things are common to mankind: the air, running water, the sea, and consequently the shores of the sea. This ancient principle was subsequently absorbed into English common law, where it was primarily utilized to protect the public’s right to navigation, commerce, and fishing in tidal waters, heavily reflecting the maritime priorities of the British Empire.

In the United States, the PTD was historically tethered to this narrow English common law framework. For most of the nineteenth and early twentieth centuries, American jurisprudence strictly limited the doctrine's application to navigable waters and the lands beneath them. The seminal 1892 Supreme Court case *Illinois Central Railroad v. Illinois* solidified this interpretation, ruling that a state legislature could not irrevocably grant the Chicago waterfront to a private corporation because doing so would abdicate the state’s unassailable duty to hold the land in trust for the public's navigational and commercial interests. Despite this forceful assertion of state responsibility, the doctrine remained dormant in other environmental contexts, viewed strictly as a mechanism for preserving commercial waterways rather than a general tool for ecological conservation.

This paradigm shifted dramatically in 1970 with the publication of a groundbreaking article by legal scholar Joseph Sax. Sax argued compellingly that the PTD was the most potent, yet underutilized, legal mechanism available for environmental protection. He proposed untethering the doctrine from its narrow navigational origins and applying its core fiduciary principles to a broader spectrum of natural resources, including public lands, air quality, and non-navigable waters. Sax contended that citizen-led litigation grounded in the PTD could effectively force reluctant administrative agencies to fulfill their obligations to protect the environment against predatory private interests and short-sighted government projects.

The influence of Sax’s reinterpretation became vividly apparent in the 1983 California Supreme Court decision *National Audubon Society v. Superior Court*, commonly referred to as the Mono Lake case. Environmental groups sued to prevent the city of Los Angeles from continuing to divert water from the streams feeding Mono Lake, which was causing severe ecological degradation. Los Angeles defended its actions by citing established "prior appropriation" water rights granted decades earlier. In a landmark synthesis, the court ruled that the state possesses an ongoing, affirmative duty to take the public trust into account when planning and allocating water resources, even if it requires reconsidering previously granted appropriative rights. This unprecedented integration of the PTD with traditional water rights jurisprudence established that the state cannot completely alienate its fiduciary obligation to protect ecological values, thereby transforming the doctrine into a dynamic instrument for modern environmental litigation.

According to the passage, Joseph Sax contended that citizen-initiated lawsuits based on the Public Trust Doctrine could serve which of the following functions?