When in fact it should be more of a what exactly is justifiable use of force kinda thing. The fact is that more knowledgeable men than I have written deaths of articles on this very thing.
Rather than quote them or pretend to speak for them I will refer you to one who has been my source on this exact type of information.
Masaad Ayobe has written a few texts that may help the OP. I have read them and took away some useful knowledge.
http://ayoob.com/cgi-bin/miva?Mercha...gory_Code=AMAB