The level of threat dictates your level of response, not the items you happen to be carrying. Police routinely carry items for multiple levels of response (mace, baton, firearm, etc.) It would be a very very poor lawyer who could not argue this. There have been plenty of police shootings where the officer did not first attempt to mace the suspect. Of course you have to be able to accurately determine the level of threat before you decide to shoot. But you have to do that anyway, whether your are carrying pepper spray or not. There is no requirement that you have to first try to kick someone rather than shoot them because kicking might work. Few would argue that someone running at you with a knife from ten feet out is not a lethal threat, and thus justifies a lethal response. Pepper spray would be a stupid response under that circumstance, assuming you had other, more powerful, choices available.