A rezoning is a legislative act, reviewed deferentially, but it is not unreviewable.

Legislative deference. Rezonings are presumed valid and are upheld if reasonably related to public health, safety and welfare. Courts do not weigh the wisdom of the choice.

Spot zoning. A rezoning of a small parcel to a classification inconsistent with the surrounding area and with the master plan, benefiting the owner rather than the community. Analyzed by parcel size, the degree of inconsistency, whether the change serves a public purpose, and consistency with the plan.

The master plan. Not binding in most states, but a rezoning departing from it requires explanation, and a record of changed circumstances since the plan was adopted is the usual justification.

Contract and conditional zoning. Rezoning subject to conditions offered by the owner is permitted by statute in many states, with the conditions recorded and enforceable. Rezoning in exchange for a bargained promise, outside a statutory mechanism, is vulnerable as contract zoning.

Procedure. Planning commission recommendation, statutory notice, hearing, and county or regional review where required. Procedural defects invalidate the amendment regardless of merit.

Referendum. Rezonings are subject to referendum in some states, which changes the risk profile of a development entirely.