"Petitioner, a not-for-profit corporation, proposed to build a congregate housing facility for the elderly, consisting of two units in a two-family house. . . . The Mount Vernon Building Department denied petitioner's application for a building permit on the grounds that (1) the proposed project would be a 'boarding house', a prohibited use under the Mount Vernon Zoning Ordinance, and (2) the planned construction violated certain setback requirements."
"The courts below correctly held that the Zoning Ordinance's definition of 'boarding house' was unconstitutional. . . . By its own terms, this definition includes even a family consisting of a father, mother and children in a rented house or apartment."