FWIW, someone in my area is currently awaiting trial on manslaughter charges. He saw a few folks in his driveway opening car doors, walked out with his pistol, one of the folks ran toward him, and he fired two shots killing the guy. It looks like the homeowner may spend a good deal of time in prison.
He might do some time, might not. That's all in how good the lawyers are at this point.
I caught a kid trying to steal my system a couple years ago. I ran after him, tackled him in the street and had to fire a shot to get him to stay put.
It was raining and I was in my underwear and barefoot, I was in bed when I heard him in the car.
I wasn't even detained. All I had to do was say that he used force in the commission of the crime and at that point I could establish having fear for my safety and the safety of my family.
Knowing the law is the way to go.
On the security subject there is plenty to do that will help prevent theft. My system is invisible. The windows are stock tint in the back, 15%, the fronts are way lighter at 30%. There are no stickers, no fancy rims, no clubs, nothing to make it look like it has anything to steal. I only have the factory alarm but I don't park anywhere that I have to worry about. I can see my truck at work and there is only 4 of us who work on the whole street. I am lucky this way but I also have the box bolted in place, the subs are recessed and held in with torx screws and the only things you can see are the HU and if the light is just right, the tweeters in the bottom of the doors.
My method has about stealthy install. A thief would rather take the sure thing that is visible than break in for some unknown commodities.