To secure the space necessary for the Barclays Center, developer Bruce Ratner relied on eminent domain. This means the state, acting on behalf of a private third party—Ratner and his Atlantic Yards project, of which the arena was but one piece—seized private property in return for money. Citizens who did not want to leave their homes were forced out, with Ratner all the while promising that Prospect Heights would be revitalized, thanks to the arena and new housing. Well, we have the arena, but there's no housing in sight, only broken promises and payments below market value.
The folks who had property taken from them banded together to file a lawsuit that was eventually tossed out by the Brooklyn Supreme Court. Progress is here, whether we want it or not.