Nor deny to any person within its jurisdiction the equal protection of the laws.
Village of Willowbrook v. Olech, 528 U.S. 562 (2000)
The Equal Protection Clause gives rise to a cause of action on behalf of a "class of one" when the plaintiff does not allege membership in a class or group, but alleges that they have been intentionally treated differently from others similarly situated and that there is no rational basis for such treatment.
City of Cleburne v. Cleburne Living Center, Inc., 473 U.S. 432 (1985)
Requiring a special use permit for a proposed group home for mentally retarded people violated equal protection. Although the mentally retarded, as a group, are different from those who occupy other facilities that are permitted in the zoning area in question without a special permit, such difference is irrelevant unless the proposed group home would threaten the city's legitimate interests in a way that the permitted uses would not.