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.

Unfortunately the law in Canada states that you are only allowed to use enough force to neutralize the situation. Of course in court laws are constantly subject to interpretation.

And remember while your lawyer might be good...his might be better.

That is the way it should be everywhere IMHO. Don't confuse a willingness to use NECESSARY force with an advocacy of using EXCESSIVE force. Determining necessary force does not entail trying each an every possible response, in order of severity, until you finally find something that works. Nor does necessary force mean that you immediately jump to the most lethal level of response. Judgment is required. Good judgment. That is why you obtain training, do research, and practice.

But I understand that laws are different in different places. Some countries do not think any assault ever justifies a lethal response. If you are severely assaulted you are expected to lay there and die rather than defend yourself. I consider myself lucky to not live in such a place. I hope to never find myself severely assaulted, but I take some small comfort in knowing I can defend myself (I practice and have gone through training, and continue to go through more and more training).