I haven't been able to get any real answers either.
I did some reading, and it looks like in AZ, the law states that for pre-employment drug screening, they have to use a lab. It seems like most labs now use an MRO (Medical Review Officer - or something like that). If your test is positive...
I have an AZ MMJ card and am thinking about looking for a new job. I know in AZ you can't be discriminated against for MMJ by an employer as long as you have a current card. (I don't plan to apply to any companies with federal contracts, etc).
I haven't had a drug test in years. I'm curious...