Good point since it says the right of the people to keep and bear arms should not be infringed I should be allowed to keep a nuclear bomb!I'm also not sure that the Second Amendment protects the right to a concealed weapon or where the definition of "arms" should end (why can't I have a M134 Minigun or Mk 19 grenade launcher mounted in the bed of my truck?). From a tactical standpoint concealing is huge, although in many situations having it in the open might work as a deterrent to some people. I don't have a problem with conceal carry if that's what interpretation is. In fact, I wish we could get there so we could cut down on the whining.
In places where conceal carry is shall-issue, it's generally not a big deal. When I lived in Alaska nobody made a big deal out of it. Hardly anybody carried concealed, even when they changed the law so you didn't even need a permit.
In states with shall-issue, the number of eligible people holding conceal permits are small (a little under 10% to well under that) and common sense dictates most of those people aren't carrying most of the time. So it makes me think that the number of possible situations where public policy becomes a question like you mentioned will be rare, but they will be high profile due to the potential for serious injury or death.
I do think that people should be legally liable start or cause a problem that ends in someone getting shot. That famous case in Florida never should have happened, and the fact that Zimmerman pursues and gets out of his car around a perceived dangerous criminal is negligent, regardless of whether it is determined to be murder or not.
I also have seen multiple news stories where people didn't secure their firearms (that they shouldn't be using anyway because the models they had were faulty) and they hit the floor and shot someone. I can remember two of those cases right now (one in a bathroom, one in a restaurant) and in both cases the individual wasn't deemed legally responsible for bad weapon retention that resulted in an injured party. At the very least they've proven they're a danger to others with firearms and I would hope that the rights of others not getting shot should outweigh their right to carry a firearm.