[AmericanChopper]

From a safety point of view, it’s difficult to test for marijuana intoxication. There’s a simple test any employer could do to test whether their forklift driver is drunk right now. The best a marijuana simple marijuana test can do is whether you’ve had it in the past few days.

[canti]

You make a decent point. This is why I mentioned a saliva test, but in truth I'm not sure how effective it is. Anecdotally, I can tell you I once smoked at night before bed and passed a saliva test the next morning.

[AmericanChopper]

I believe they do that for police roadside tests in Australia. From what I can gather they have a rather bad reputation for not correlating very well with intoxication.

BAC is a well understood thing to measure, but marijuana testing seems pretty unreliable to me. I’ve read conflicting reports about how strongly TCH found on a saliva swap correlates to actual intoxication, and I don’t believe there’s been much scientific investigation done to determine what levels of intoxication are safe for what activities. As the primary customers of these products are law enforcement, and private sector “rules enforcement”, I’ll remain skeptical of them until somebody manages to convince me otherwise.