I've never heard of that concept, I would think most people would want more then one person to have access to one gun,for example if I had already been shot I sure hope my wife would be able to pull the trigger. Assuming it's impossible for anyone to manipulate the system, and it never has any glitches I have no problem with that concept. It seems like you might run into problems creating something that passes that criteria, but to that I say try harder or deal with the fact you won't find agreement. I get that these things all sound paranoid, but the 2nd amendment rights are that critical. This is where the sacrifice has to be made. If there were 10 of these mass school shootings a year I'd probably be willing to agree with you but something this rare as tragic as it is has to be put in the proper perspective. Just like auto accidents or plane crashes we have to weigh the good with the bad. Maybe you don't think the good amounts to as much as I think it does, but we could start banning a lot of things if we focus on the worst things that ever happen as a result.