I wonder how this is going to work out for industries like the railroads, airlines, trucking companies, etc.
I can only speak for the railroad, but the FRA policy for train and engine employees that there could be no drug use on or OFF duty.
That means, none at all, not ever.
T&E were subject to random drug tests, and off-duty usage could be detected through such tests.
I got caught for opium once (drug test after having a hard roll with poppy seeds on it for my supper). Had to talk to the head Company medical officer and have my arms examined for needle tracks (but still worked the next day).
Now we all know that alcohol, while legal, is also "banned", in that one cannot be under the influence on duty (they had breathalyzer tests, too).
But... its use was still permitted off duty (so long as one showed up for work NOT under such influence).
But what about marijuana?
How will the FRA (and other agencies such as the FAA) reconcile the fact that mj is now "legal" under federal law, but still forbid its off-duty usage?
Gonna have to see how that plays out.