I would not want to take someone's life simply because they were stealing from me. Nothing I own is worth a life, not even the life of a bottom-of-the-food-chain, pond-scum sucking, sub-human theif.
However, there is no law on any book that requires me to simply stand by and watch someone walk off with what's mine.
As far as I can tell, it is within my rights to stand between a theif and my property, or remove it from his grasp. Morally and ethically, and legally, I can do just that.
If you cannot protect what's yours, then you own nothing.
Now then, if the BG (aka: bottom-of-the-food-chain, pond-scum sucking, sub-human theif,) chooses to "take it to the next level," that would be his (it's) choice, not mine.
As weird as things get in court, I hope I never have to argue this in front of a jury. But as a matter of principal, I think the train of thought is on solid ground.
Fortunately, if you find a theif, you've found a coward. Faced with an angry, armed property owner, they tend to run. If not, then whatever they may do next would likely be a "forceable felony*," and as such, they are elevated to the rank of "legitimate target." (* in the state of Florida)
Of course, I'm not a lawyer, but I have seen them on TV.