Cops must be able to use their tazer anytime, -1. but the thing that i'd notify about is to make the cops disallowed to kill the felons after tazing them even tho they got attacked, but nowadays they're using it to make the struggle easier to win.
Of course it bothers for the criminals when the fight cops but somehow cops must be allowed to use it might to protect themselves from getting killed if they weren't as strong as the enemy is, but in my look still the main purpose of using tazer is to arrest.