By a 4-3 vote, the Court of Appeals held in People v Weaver (5/12/09) that the New York Constitution requires that a warrant issued upon probable cause be issued before the police can monitor someone's whereabouts by surreptitiously attaching an electronic device (GPS) to that person's automobile. An excellent summary and analysis of Weaver can be found at New York Court Watcher.
A contrary holding would mean that police without warrants or cause could attach such devices to all vehicles in New York and record the minute by minute location of every vehicle. There may be places where that is acceptable. Thankfully, New York is not one of them.