Never bring your personal cell phone powered on with cellular, wifi, and bluetooth enabled (and outside of a signal-blocking pouch) to protests unless you want to be added to watch lists and be "random selected" for "enhanced screening" at airports for the rest of your life.

Color me shocked. I'd have never imagined that they'd detect such a thing from the honest, law-abiding, rules-beholden public servants of ICE and its federal law enforcement colleagues.

Seriously though and on a practical note, anyone who really does care about their identity being revealed, or getting nailed by some kind of law enforcement crackdown/harassment on traced and identified participants after a protest should simply not bring their phone to one of these events, at all.

If you really need communication during, get a burner right before the event, buy it with cash, preferably somewhere where a dozen cameras don't get your face plastered all over them (and while not having your normal phone with you when you go buy the burner), and dont download any apps with personally identifying accounts to it. After, toss that same burner phone right away or deactivate it completely. well before coming back into proximity of people you normally know, your home, or places you frequently habituate.