My nephew was involved in a shootout, chase, shootout, car assault, chase, rollover, shootout type deal that all started when a Boulder, CO police officer tried to subdue a suspect with a taser. It did not incapacitate the suspect, and he drew a gun and shot two officers, shot at some teenagers, and then tried to run over two other cops (my nephew being one) before being rammed and shot to death by another police officer.
If guns are not an option, I say buy the best pepper spray to be had. I had over 400 hot pepper plants in the garden one year(412, to be exact), and had the unfortunate idea of grinding up some cayenne an habeneros for relish. I think I got a healthy shot of high test capscium due to bad blender operation, and was DEFINITELY incapacitated for 15+ minutes.
Oh, and if you are canning hot peppers, wash your hands THREE times before relieving your bladder...