A and B each have $50,000 to invest. A purchases a vacant lot for $50,000. Ten years later the city passes a zoning ordinance zoning A's land for single family dwellings. The value of A's land is reduced to $12,500 by this action.

B purchases the vacant lot next to A's lot for $10,000 and builds and equips a store on the premises for $40,000, for a total investment of $50,000. The store earns B a 10 percent net profit each year after paying all business expenses including B's salary. After 10 years the city passes a zoning ordinance zoning B's land to single family dwellings. The value of B's land, like A's land is reduced by three-fourths. If ordinance requires B to discontinue his nonconforming use immediately, the courts almost surely would declare it unconstitutional as a taking of B's property. Why would this be so? Is B more harmed than A? If the ordinance were retroactive, would you prefer to be in A's or B's shoes?