Fire someone for showing up to work drunk, sure. But would you fire them for a bottle of wine on a Saturday night?
If alcohol was like THC (that is, it's impossible to determine whether you drank in the last hour or the last week), I sure as hell don't want people who test positive driving.
That, plus marijuana is still illegal in most states. Whatever your personal conviction may be, businesses aren't in the business to turn the blind eye to illegal substance use. They're on the hook for liability.
NPR recently pointed out that if you include medical marijuana this is no where close to true with it being legal in 29 states: https://en.m.wikipedia.org/wiki/Legality_of_cannabis_by_U.S....
So as far as I know, there isn't a reliable and accurate way of testing.
Roadside DUI test is a general test for motor impairment. BAC tests are a nice proxy for that in the case of alcohol, and a legally convenient one as they are precise and objective, but the police care (morally speaking) about your motor impairment not your BAC.
tl;dr, we can already answer the question "is this person too stoned to drive?", roadside DUI test.
There's tons of (acceptable) prescription drugs that have a worse effect on performance than THC being in your system from the weekend before. Someone's glucose level being outside the norm would have a larger effect.
> Work places (particularly those with high safety concerns) shouldn't make any sacrifices just because something is socially acceptable.
Should it be illegal to be on the job while sick? Good luck getting that legislated.
We do have some understanding and data: very slightly, the most consistently measurable affect being minimally impared depth perception. Treating marijuana intoxication as a high risk imparment to motor function is making a mountain out of a mole hill. Relating the equation of motor function impairment caused by marijuana to that of alcohol or for that matter many other intoxicants (including a multitude of very commonly used pharmaceuticals and stimulants) sure seems a bit ignorant or uninformed to me. I'm not advocating marijuana use, especially when performing potentially dangerous actions that require attention and possibly urgent corrective action (driving, operating dangerous equiptment, performing surgery, etc.). But do consider there's plenty of professional athletes who have preformed some of the highest level coordination, precision and reaction time dependant functions of humanity while being under the influence of THC. Sorry to rant, but I think it's important to remember that people using alcohol cause an awful lot of harmful, deadly, and easily avoidable accidents. DUI's and similar restrictions are a direct result of that fact. I've looked for but have never seen evidence that shows an even remotely similar risk from THC consumption. If anyone is aware of data indicating otherwise, please share.
I think you misunderstood the MJ testing. MJ stays in the blood stream, and you can be caught by a random drug test on Tuesday for that joint you had on Saturday.
OP was not, I think, arguing for working 'high'
Perhaps (and I'm granting some leeway here) we don't yet have the tools or the data to understand well enough how something like THC affects motor skills like we do with alcohol, but someday I expect we will. Work places (particularly those with high safety concerns) shouldn't make any sacrifices just because something is socially acceptable. You can't show up drunk, and alcohol is more socially accepted than marijuana.