I assume you're referring to the death of Rayshard Brooks with your DUI comment. In that specific case, the police officer only shot once Brooks shot at him with the stolen taser. At that point, I suspect the argument he'd make is that he believed (rightly or wrongly) that his life was in imminent danger and he was ending that threat. I doubt he shot to apprehend the fleeing suspect, which would go against his training and is in fact illegal under such circumstances.

There's a larger issue, though. All laws ultimately are enforced by people with guns who will do violence up to and including death if people don't comply. Some laws are less likely than others to result in death (e.g. drug laws vs. securities fraud), but "is this law worth killing for?" is a question we all should ask when considering what the law should be.