Accession, Riparianism, and the Colorado Doctrine
Abstract: Economic scholarship on property scholarship has studied common law property rights in river water as a test case. In the mainline interpretation, rights in river water evolved from a commons, in the riparian eastern U.S., to property rights, in the prior-appropriation or Colorado doctrine, prevalent in the western U.S. This transition seems to confirm Demsetz's evolutionary theory of property. This mainline portrait misses the role played by policies and high-level legal principles that regulate “accession,” or the legal question how property law identifies the legal “things” that have property rights. In legal terms, the shift from riparianism to the Colorado doctrine consists not of shifts between common and private property, but instead between two different bundles of private property rights. To respond to river water's low value in the east, property law makes that water not a commons but a legal accessory to ownership of riparian land. In the arid west, river water ceases to be an accessory and becomes a separate object of property--and rights in land are correspondingly limited by ditch easements. Accession and thing-delineation don’t refute Demsetz’s theory of property. But they do show that Demsetzian evolution can proceed through a second process, every bit as important as the move from a common pool to private property. This article identifies the strengths and limitations of scholarship on water rights by Gary Libecap, Terry Anderson, Carol Rose, and Dean Lueck, and also recent scholarship on accession by Thomas Merrill.
