In many states it's not an affirmative defense but rather "defense of justification." And at no time must you say what you did or why you did it. The prosecutor must make a case against you without your statements. He must show why the person in your bedroom during the night didn't intend harm. And it doesn't matter much in some states anyway. In NYS deadly force can be used to thwart a burglary. "Thwart" a burglary.
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You don't plead the fifth. That's to protect you from self incrimination. You just don't speak at all. You aren't required to make a statement or testify. It's the innocent who need an attorney. Let the guilty lie for themselves.
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However, what I recommend in PP classes is to simply tell LE that you have nothing to say at this time but will gladly answer questions after you've had a chance to retain an attorney. Then shut you mouth. Not another word. Not even casual conversation. Nothing!
I want to be clear that I’m not talking about the immediate aftermath of a self defense shooting. I’m talking about after you’ve had time to sit down with your lawyer go over your version of the facts and prepare a statement (if any is going to be given).
If any statement is given you are going to be admitting to homicide / attempted homicide (the killing of a human being by a human being). In fact you probably admitted to homicide at the scene. “ Officer that man was attacking me and I was forced to fire in self defense.” (that’s an admission).
So at some point in the process you are going to say ”I shot that man and I was justified in doing so because….”
That’s why I said you had better be able to articulate specifically what that guy did that made you think he needed shooting.
As an example there was a thread a few years back on ar15.com in which the author advocated that if two “perps” are approaching you at night in a parking lot you should let them know you’re armed. If letting said “perps” know you’re armed doesn’t work you should draw on them.
Now imagine yourself articulating specifically why you drew on these guys.
Officer they were walking toward me in the parking lot and I got scared so I drew. (let me know how that works out for you).
Now imagine the example I used earlier “ I was awakened by a noise coming form the living room of my home. Upon investigaiton I found the deceased who had unlawfully entered my home in the living room. It was dark he appeared to have something in his hands. I ordered him to leave my home and he became aggressive, threatened to kill me and advanced in my direction, I was forced to fire in self defense.