So what could be done, legislatively and enforced, that would not hinder ourselves from obtaining such a rifle, but could have prevented this off-kiltered 18 year-old from purchasing these weapons with which he carried out this deadly crime?
The mechanism to do that is in place, and has been for a long time. The drawback to it is that it must have a set of standards, to give everyone equal treatment under the law, AND the responsible authorities not only need to recognize there is a potential threat, they also have to correctly evaluate the risk and IF it meets the standards set in law, act in a competent and timely manner.
Suppose they look at 100 "off kilter" kids over a few years, and none of them is ruled to be a credible threat, and none of them ever do anything. The people doing the assessments, get their faith in their judgement re-enforced, after all, they's been right 100 out of 100 times.
Then they look at kid #101...see the same things (essentially) they've seen before, and rule #101 no real threat. All good, still..right?
Then, years later, #101 (who is not restricted) buys guns and goes on a murder spree.
What failed there??? Did the system fail?? Did the evaluators fail? Or maybe kid#101 decided to actually go on a murder spree sometime AFTER being evaluated??
As to "hardening" our schools, AB, I know its your area of expertise, but I have to slightly disagree with this statement.
It's a design issue, not a code issue,...
I don't think its a design issue, directly. Designers will create whatever code requires. If you put security concerns into the building codes, designers will come up with something to meet code. If you don't, they won't.
ALSO one has to look at conflicting needs in design codes. And prevailing thought at the time. Look at commercial aircraft cockpit doors. Until the codes were revised after the 9/11 highjackings, cockpit doors were required to be easy to break into.
This was a safety concern. The concern at the time the standards were written was that if something happened to the pilot(s) (and the door locked) someone else on the plane could break into the cockpit and hopefully keep the plane from crashing. That was then, this is now and priorities have changed.
But consider, about building codes, the priority has always been safety of the people inside, and this includes getting them out safely and rapidly when needed, such as when there is a fire. Keeping people out has always been a much lower priority, if it was even on the list.
Lots and lots of our kids are still going to school in building that were created over a half century ago, or longer. In the late 60s I went to the same school building my mother graduated from in the 50s, and its cornerstone had the construction date on it, 1936... it was a junior high for me, it had been her high school. In the early 70s I went to the new high school, a building that had just been finished and opened a couple years before I got there. I'm sure there are still school building in use that were built in the 70s or even before in many places around the country.
its a balancing act, and the thing weighing very heavily ALL the time is money. New concerns have to not only be possible, but practical enough to balance against their costs.
Doing "anything" and spending as much as needed to protect our kids is an ideal and makes for a compassionate sounding sound byte, but in the real world, compromises (and not always good ones) WILL be made and reality often falls short of our ideals.
If you can change that, we've got something to really work with.