tl;dr: Multiple police chiefs and officers have been caught using Flock's license plate reader system to stalk romantic partners and rivals—including an Illinois chief who ran an ex-girlfriend's new boyfriend's plate 178 times—with the Institute for Justice documenting at least 18 such cases. Flock publicly claims it tracks vehicles, not people, but its own Chief Legal Officer admitted stalking is "the most common" abuse of the system. Civil liberties groups argue warrants should be required for LPR searches, as already mandated for GPS trackers, cell location data, and wiretaps.