The decision, the first federal ruling to find that the practice under the Bloomberg administration violates the Fourth Amendment protection against unreasonable search and seizure, focused on police stops conducted in front of several thousand private residential buildings in the Bronx enrolled in the Trespass Affidavit Program. Property managers in that program have asked the police to patrol their buildings and to arrest trespassers.
This is one of those awkward clashes between public safety and the 4th Amendment. DUI checkpoints are analogous, but have been upheld time and time again. Granted, a drunk driver poses a significantly greater danger to the public than a trespasser in an apartment building might, but it's a difficult distinction. Will be interesting to see how they refine the standard for stops and whether it actually works.