Natural Resources and Natural Law Part I: Prior Appropriation analyzed claims by some western ranchers, grounded in natural law, that they have property rights in grazing resources on federal public lands through prior appropriation. Those individuals advocated their position in part through civil disobedience and armed standoffs with federal officials. They also asserted that their duty to obey theistic natural law overrode any duty to obey the Nation’s positive law. Similar claims that individual religious beliefs override positive law have been made recently regarding a range of other controversial issues, such as same-sex marriage, public insurance for birth control, and the right to bear arms. Prior appropriation doctrine is consistent with secular natural law theory. Existing positive law, however, accepts prior appropriation for western water rights but rejects its application to grazing rights on federal public lands, for reasons consistent with secular natural law. Natural law doctrine allows citizens to advocate for change but requires them to respect the positive law of the societies in which they live. Separation of church and state also bars natural law claims based on religious doctrine unless those principles are also adopted in secular positive law.

This sequel addresses claims from the opposite side of the political-environmental spectrum, that natural law provides one justification for the public trust doctrine, and that courts should enforce an atmospheric public trust to redress catastrophic global climate change. Although some religious groups have embraced environmental agendas supported by religious doctrine, public trust claims are secular in origin. Just as natural law provides support for prior appropriation, it supports the idea that some resources, such as water, wildlife, and air, should be held in common rather than made available for private ownership. From this perspective, the two doctrines merge into a single issue of resource allocation. Which resources are best made available for appropriation as private property, and which are best left in common? Natural law theory helps to explain the liberty and welfare goals that inform those choices. Positive law embraces the public trust doctrine with respect to some natural resources, and does not preclude its applicability to the atmosphere or other common resources.