Zoning ordinances sometimes are challenged on constitutional grounds other than those based on the Due Process and Takings Clauses. This chapter discusses some frequently encountered challenges.
The highest zone or district in cumulative, Euclidean zoning ordinances is the “single family” residential-use-only district. Defining a “single-family residence” is an important, oft-litigated issue. The definition excludes apartments, boarding houses, multi-family residential uses, and “nonresidential” uses, including retail and other commercial activities. But a boarding house, group home, or student housing may have the outward appearance of a single-family house, but not be inhabited by a family. Many ordinances, however, define single-family residences in terms of the number of people and the legal relationships of those persons as constituting a “single family,” often also limiting the term to persons related by blood or marriage, or to a maximum of three to four persons unrelated by blood or marriage. The issue is the extent to which the state may regulate the composition of households as “single families.”