Self-defense

There is no defense against "blitz" attacks by psychopaths-- they will wait to isolate a victim and wait until the victim is not in a position to defend. It will be over before you know it started- or even suspected it would start! The only defense against that is to AVOID being alone with psychopaths!! For all the other situations, I suggest a combination of technologies that already are used. Tear gas. Dye packets. Noise. Light. Flash grenades! sure, why not. All in one- and when you feel yourself fading from "roofies", or the Uber driver gets in back with you, or you are limping along the street and a group of kids approach you and won't back off when you yell at them---- you simply detonate "the device". Sure- it will hurt you somewhat- and make a mess- and automatically notify the police (and maybe even send a bat-signal to the sky??)... but it will also change the course of "history"-- you will not likely be harmed by others- you and everyone near you will be harmed BY YOU. And because you also are "in it", you can't be accused of being violent or intending to hurt others- it WAS self-defense and your injuries, being at the center of it all, are solid gold proof it was self-defense. Maybe a modification would allow the device to be tossed upward- and detonate in a way that favored injury to those not exactly where you are standing.