A news report I read was that they were his father's firearms, legally obtained by the father.
How would I set limits of reasonable security? Well, starting with a gun safe (or a 'real' safe), and anyone having to defeat the safe to obtain the firearms would let the 'owner / possessor' off the hook. Letting a minor know the safe combination (ah la Sandy Hook apparently), would put the blame squarely back on the owner.
So let's say you have a firearm. If not in use, it should be in a 'safe' and anyone who takes it from that safe should have to cut his / her way into that safe. Family members who know the combination means to me that YOU, the firearms owner / legal possessor, "let" them have your firearms. And as such, you bear responsibility. Now, suppose you have a firearm on your person: someone should have to physically assault and overcome you to take possession of that firearm.
I think in reality, without a lot of written laws, we can determine the path that one takes to obtain a firearm and how difficult or available that path was. That would set the pace of the charges and trial, IMO. The law recognizes intent, and if your clear intent was to keep your firearms secure, you <should> be relatively safe from criminal and probably civil prosecution. That is what I would use for a standard.
If I were to have firearms, and I am not saying I do, but if I did, you would have to make substantial effort and risk 'life and limb' to maintain possession of them. I feel I bear a responsibility to the society I live in to be responsible with and for them, within reasonable bounds.
As far as your litany of questions, all I can say is that I do not necessarily support more laws, such as securing firearms, but I do believe in responsibility. If one is going to bring a firearm to the proverbial 'party', then it is the responsibility of that individual to retain said firearm and not let it "loose" in any environment, at home or outside the home. I support one's right to carry a firearm in, say, a Walmart for personal defense but would not look kindly toward anyone who had a firearm 'slip away' at that same Walmart in any kind of confrontation or melee. The general field is called 'weapons retention' and I firmly believe if one chooses to posses a firearm, then one has fundamentally agreed to reasonable limits on retaining said firearm(s).
There is no need for any additional legislation IMO. All that is needed is for one person to be charged, to set precedent, and let a jury decide if that person was at fault, and possibly [how much] fault.
Brian
We don't know anything about HOW he obtained those guns yet (unless you know something I don't about it). For all we know, they were locked and he defeated the security, similar to a robbery. Would it just apply to minors? Just to family? People you know? If a robber broke into my house and took my car, knife, locked gun, axe, rat poison, gasoline, etc and killed or hurt someone using one of them, is that my fault? How much fault? How "locked" or "secured" is enough? If there is liability, could landlords then be liable too? Would they start to restrict what renters could possess? Would we have to carry additional insurance? Would this require inspections?
I totally agree, but legislating that is very tricky. Like I said in my previous posting, this will be the new narrative now...
Edited to add legislation thoughts.