I don't think it is legal vis a vis the 4th amendment. It seems that the FLOCK company devised a surveillance system, then simply sent salesmen out to police authorities to sell them on the idea. Which, of course using public money the cops said, "HELL YES!"
The issue here is that there was no enabling legislation. Ergo, there is NO OVERSIGHT on useage of the data, there is no set of rules regarding security of the data, there is simply no legal structure at all. Cop-stalkers by the hundreds are using it to stalk ex-wives, girlfriends and so on. Yes, they get exposed in a few cases, but there is no penalty of law.
I know people are trying to apply the notion of "no expectation of privacy" but that is not the right standard here, because this is a surveillance data base, and it is 100% unknown who has access and for what purposes.
Maybe even more important is the psychological destruction of the population's belief in FREEDOM. This is a corrosive project for public belief system.