public trust doctrine

Definition from Nolo’s Plain-English Law Dictionary

The principle that certain natural and cultural resources are preserved for public use, and that the government owns and must protect and maintain these resources for the public's use. For example, under this doctrine, the government holds title to all submerged land under navigable waters. Thus, any use or sale of such land must be in the public interest.

Definition provided by Nolo’s Plain-English Law Dictionary.