In a major property rights decision, the U.S. Supreme Court has delivered a decisive victory to state and local governments and environmental groups. By a 5-to-3 vote, the justices made it much harder for property owners to get compensation from the government when zoning regulations restrict the use of just part of landowners’ property. The Constitution bars the taking of private property by the government without just compensation. The Supreme Court, for a century, has said that when the government goes “too far” in regulating property — so as to make that property economically unusable — the government also has to compensate the owner. The question is: How far is “too far”? In recent decades, property rights advocates have aggressively tried to limit regulation by demanding compensation. At the same time, cities and states have sought to manage urban sprawl, water pollution, flooding and other problems, by enacting regulations to limit what some property owners can do with their land. Friday’s decision came in a case that involved two plots of land, bought by William and Margaret Murr in the 1960s, overlooking the picturesque grandeur of the St. Croix River in Wisconsin. In 1972, the river was designated for federal protection, and the state enacted regulations to preserve its scenic and recreational qualities. The regulations barred building on any lots smaller than one acre of land. The Murrs’ two lots, including a cabin on one, combined to cover just under an acre of land suitable for development. Under the regulations, the lots were merged into one. After the Murrs transferred the property to their four children in the 1990s, the younger Murrs were denied permission to build on what had previously been the second lot….