Ps own properties in the District of Columbia. One is a department store and another is a retail hardware store. Ds are members of the District of Columbia Redevelopment Land Agency, a corporation. The properties of Ps are located within the boundary lines of an area known in this litigation as 'Project Area B'. D published a Comprehensive Plan for the whole District of Columbia. Then it prepared a 'Land Use Plan' for an area called the 'Southwest Survey Area', which includes almost the whole of Southwest Washington. The surveys conducted on the land showed that for 1345 dwelling units in 1006 structures with 5000 plus people that 57.8 percent of the dwellings depended upon outside toilets, 60.3 percent had no 'baths', 82.2 percent no washbasins or laundry tubs, 29.3 percent no electricity, and 83.8 percent no central heating. The survey indicated that 64.3 percent of the dwellings in the area were beyond repair and 18.4 percent needed some major repairs. D then advertised for proposals to negotiate for the purchase or lease of land in the project area. It accepted the proposals of five bidders who owned property in the area (Safeway Stores, Inc., Martin Wiegand, Inc., Eagle Transfer Company, Max Greenwald, and Rudderforth Brothers), each to repurchase its present property, and of the Bush Construction Company for the remainder of the area. Project Area B is a slum area. The plan requires that not less than one-third of the dwelling units in the area shall be low-rent units, which means that the maximum rental shall be $17 per room per month, excluding utilities. The critical features of the statute are premised upon the police power of the state -- public health, safety, morals, and welfare. Ps claim the Act is unconstitutional because it authorizes the taking by eminent domain of the fee title to private property and the sale or lease of that title to other private persons for private uses; and that D authorized the taking of property in 'blighted areas' without defining that term and thus fails to establish any standard sufficiently definite to sustain the delegation of power. Ps claim that the statute should be construed strictly and, as thus construed, does not apply to commercial property or to any property upon which slum conditions do not exist. Ds claim that the elimination of slum areas, injurious to the public health, safety, morals, and welfare, is a public purpose; that the condemnation of title to the property in the entire project Area B is incidental and essential to the elimination of the slum area.