The use and application of variances can differ considerably throughout the great number of municipalities worldwide that regulate land use on this model.
This can depend on a municipality's regulations, built environment and development pattern, and even political climate.
Typically, in the United States, the process for a variance must be made available to a landowner upon request, or the municipality may be in danger of committing a regulatory taking.
It can be requested by a builder or landowner when an odd configuration of the land, or sometimes the physical improvements (structures) on the land, requires a relaxation of the applicable regulations to avoid denying the landowner the same rights and use of the property enjoyed by owners of neighboring properties.
In either case, the variance request is justified only if special conditions exist on the lot that create a hardship making it too difficult to comply with the code's normal requirements.
Likewise, a request for a variance on a normal lot with no special conditions could judiciously be denied.