In Berman v. Parker (348 U.S. 26 (1954)), DC was trying to rehabilitate a "blighted" area
of the city. Most of the homes were completely beyond repair and abandoned. However, there was a department store in the rehabilitation zone that claimed it was not "blighted," and sued to stop the city from taking the property via eminent domain. The store wanted the city to assess each property individually, but the US Supreme Court found that eminent domain should be decided "as a whole," and not in a piecemeal fashion.
Basically,
this case established that the government can use eminent domain to rehabilitate a "blighted" area,
even if they intend to simply give the land to a private developer, and
even if not every single building within the area is "blighted."
Compare
this to the later case of Kelo v. City of New London (125 S. Ct. 2655 (2005)). There, the US Supreme Court
expanded the power of eminent domain to allow the government to use eminent
domain to rehabilitate an area that isn't blighted at all.
In
this case, the city was
attempting to build low-income housing that would theoretically be
enjoyed by the same people who were being kicked out. In Kelo, the city was going to build
an industrial park, which would not directly benefit the people who were
being kicked out.