Originally Posted by BlackFeather
...I don't want to put this in a specific situation, as it's irrelevant....
Actually, it's not irrelevant at all. In fact, it could make all the difference.
First, where something might happen is important because the outcome will depend on the applicable law where the event takes place. Second, exactly what happened and exactly how it happened, and how the law applies, will decide the outcome.
So in your case of an innocent bystander getting shot by accident as a result of the "good guy's" attempt to disarm a "bad guy", the bad guy could certainly be held responsible. But depending on exactly what happened and how it happened, and depending on the applicable law, it's not inconceivable that a jury would also find the good guy liable for civil damages if the jury concludes that he was unreasonable in attempting the disarm.
This is one of the kinds of questions where "the devil is in the details." Depending on exactly what those details are, the outcome can range from the injury to the bystander being considered a sad but unavoidable accident to it being considered the result of an act of extreme recklessness on the part of the good guy for which he could be held criminally and/or civilly responsible -- or something in between.