New York thugs want to spy on everyone's email looking for signs that someone is preparing to commit mass murder.
This could really mean plans to entrap people, most of whom would never have tried to kill anyone. Even psychiatrists can't predict which of the many mentally ill people are the tiny fraction that will become violent; but the NYTD won't try to predict so much as to entrap them all.
Unrestricted state surveillance is a bigger danger than individual mass murderers. The NYTD has been accused by the UN of systematic violence against dissidents.