The Fifth Amendment to the Constitution, and comparable provisions in state constitutions, bar the "taking" of private property by government unless just compensation is paid to the property owner. Initially, the Supreme Court recognized only government seizures and physical invasions of primate property as "takings." Thus, recurring flooding of a farm as the result of a government dam would probably be a taking. In 1922, the Court expanded the concept of takings to include government actions that merely restrict the economic use of private property, if that restriction is severe enough. However, the line between restrictions that take and those that do not has proved elusive; the Court repeatedly stresses that the determination is an ad hoc, case-by-case one. The agricultural community perceives a threat of takings from federal efforts to preserve wetlands and endangered species, though actual court decisions finding takings of farmland are few. The takings issue has also worked against farmers by virtue of a recent case striking down a "right to farm" law that curtailed the right of owners of residential properties adjacent to farms to sue for nuisance based on farm operations. That law was held to effect a taking of a negative easement of the adjacent properties.