Armed self defense is justified in situation in which a reasonable person believes they’re being threatened with death or serious bodily harm. That’s the general standard by which the police and prosecutors examine self-defense shootings.
Once an attacker starts to leave — whatever he may have said, done or stolen — he no longer presents a threat. And that’s why shooting at a fleeing attacker is a very bad idea.
Take, for instance, this example from Michigan earlier this week:
Police determined the shots stemmed from a incident at the [apartment] complex that had just occurred when two armed men robbed a 19-year-old apartment resident of cash from shoe and drug sales, police said.
As the two suspects were leaving the area, the resident retrieved a handgun and opened fire on the two men, striking several parked cars and an adjacent building, police said.
As soon as the two turned to leave, they were no longer a threat to the un-named 19-year-old. Getting a gun at that point and squeezing off a few shots at them only made a bad situation worse. It opens him up to charges such as negligent use of a firearm or reckless endangerment. And if a stray round hits someone, it only gets more serious.
This was apparently a drug sale gone wrong (what are the odds?). So the 19-year-old here will probably be facing other charges as well. But that’s beside the point. If it had been a garden variety mugging or home invasion, once the attackers left, the best course of action would be to lock the door and dial 911. The freedom and gun rights you risk by shooting at a fleeing attacker may be your own.