Well, this case en.wikipedia.org/wiki/Florida_v._Riley pertains to your question. Some of the dissenting opinions raise the same questions you do, but there's a reason I had to call them 'dissenting opinions'.
If indeed these drones are using Dirtboxes and are indiscriminately tracking people based on cell phone signatures, then I would posit that the combination of [1] and [2], and ongoing issues like [3], make what law enforcement is doing Baltimore disgustingly illegal and oppressive. Targeted and specific aerial imagery and inspection is a totally different ballpark than what these drones are doing.
