I smoke a little pot, on occasion, and I don't advocate the Fed getting involved at all and would reluctantly accept a State solution, because there isn't a problem, IMHO.
There are much more kids TXT'ing while driving and killing than driving while stoned.
Address the REAL Problem, reprobates among US.
Yabbut, cell phone possession is legal, and not just for medical purposes.
It isn't just kids, I have seen middle aged people who were so involved in their phones they sat through green lights. It gets worse in motion.
But outright legalization means it's okay, right? (as in socially acceptable).
If that happens, it will be used on the highways even more, and despite all the gadgets to keep us all safe (seat belts, air bags, side air bags, crumple zones, telescoping steering columns, lane warning devices, blind spot indicators, etc.), more people will die.
We have known drunk driving was a problem since the first drunk fell off the freight wagon and got crushed under the wheels, and the problem hasn't gone away.