Or in the defense of another. It wouldn’t make sense for a robot to take a life to save its own, but it might make sense for it to take a life to save your mother’s.
This is a horrifically terrible idea.
It is imperative that a human always be a decision maker about lethal force so proper judgement can be made and someone can be held accountable if it is made badly.
We have serious problems with accountability of law enforcement in the US.
So what, you go up to a bank, with a fake gun, and then say "lul, I was just robbing you as a prank bro?"
Probably the same thing will happen to you, as would happen to you right now, if you pointed a fake gun at someone.
The person pointing a fake gun at someone, would be the one shot either way, even if a robot did the shooting.
Also, criminals will know the robots have these capabilities, too. If a barricaded suspect hears or sees a robot rummaging around, that could be interpreted as force escalation. Which may cause the criminal to react in unpredictable ways that increase risk to the public and police officers.