For your consideration ...
Now, after this passes, just watch the legislature in Annapolis think of a myriad of things for revenue enhancement, er, under the banner of safety, such as driving while high. First they'll have to establish the amount of THC in the blood number, then it's off to the races. Forget that THC can remain in the blood well after, days even, one gets high. And of course the police are already trained on how to spot if someone is high on cannabis. And since doing a drunk walk and reciting the alphabet backwards or forwards doesn't apply here, soon, all police will be trained phlebotomists as well. If not, the perp is driven to the nearest medical establishment for a blood draw. This, and many things more, yet to come from Annapolis. Just like with alcohol, only worse.
I wouldn't put it past them to pass a law that after any vehicle accident, all drivers involved will be required to get blood test for THC, regardless of who was at fault. Smoked some weed last week, not high, but with THC still in your system? Tough luck.
This can be a dangerous thing that is about to happen. Because, as we all know, until the Feds remove it from the illegal drugs roster, anyone convicted or any coming law, or that is a known user, will loose their 2nd Amendment right. In addition to still being able to get arrested by any federal agent.
So tread carefully in this up and coming minefield of legalities.