Spot zoning is the application of zoning to a specific parcel of land within a larger zoned area when the rezoning is usually at odds with a city's master plan and current zoning restrictions. The rezoning may be for the benefit of a particular owner, and at odds with pre-existing adjacent property owners. The Standard State Zoning Enabling Act states "all such regulations shall be uniform for each class or kind of building throughout each district." Courts may rule certain instances of spot zoning as illegal.
Such a change may have a legitimate use, such as when a community wishes to have more local control of land use. This may occur in a rural county which has no zoning at all, where a village or hamlet may wish to maintain its characteristic feel and historic appeal (often to protect tourism), without adding another layer of local government and taxes by creating a municipality. The county designates the boundaries (often that of an already census-designated place) and maintain regulations through the county commission instead of a separate town council.
It may also be invalid as an "arbitrary, capricious and unreasonable treatment" of a limited parcel of land by a local zoning ordinance. It is an invalid exercise of authority, if spot zoning is not a right conferred upon the body by the state's zoning enabling statute, because it deviates from the plan set out by the enabling statute.
Generally, zoning is a constitutional exercise of a state's police power and so spot zoning would be a constitutional exercise of zoning power by a local zoning authority if the state zoning enabling law allows spot zoning.
Spot zoning may be an invalid exercise of a local authority's zoning power if the state zoning enabling law prohibits spot zoning. While zoning regulates the land use in whole districts spot zoning makes exceptions for parcel/s within a district.
Situations where spot zoning may arise
A variance is the license to deviate from the land-use restrictions imposed by the zoning ordinance. A variance usually requires the landowner suffer a substantial hardship which only the granting of a variance may remedy. If a local zoning authority decides to grant a variance to a landowner who lacks substantial hardship, then its legality (regarding equal protection) may be called into question.
A special-use permit occurs when a zoning regulations allows some specific exception to its regulations provided that a landowner receive a special-use permit from the local zoning authority. An example of a specific exception includes a church in a residential neighborhood. If the special-use permit deviates from zoning ordinance or the enabling statute, then an instance of spot zoning arises.
Amendment to ordinance
A local zoning authority like a city may seek to amend its zoning ordinance. If it amends it zoning ordinance but only for a parcel within a district and the parcel has a different land use characterization than the surrounding district, then an instance of spot zoning arises.
Contract zoning occurs when a local zoning authority accommodates a private interest by rezoning a district or a parcel of land within that district. Then the private interest may then be allowed to develop the land where before the zoning regulations prohibited such a land use. This is spot zoning in all instances.