A couple of observations;
1) Everybody knows what the rules are (or should). Get caught and that's on YOU.
2) I notice in 99% of these cases, the person never tells us what the taking or why, so I am going to 100% of the time assume that means it's an illegal substance.
3) If you NEED to take ANY type of medicine, supplement ETC, it's on YOU to confer with the sanctioning body and get written approval or find an alternate product that meets their criteria. The excuse of "I didn't know " went out the window a LONG time ago. Under a FAR less stringent testing program, I took the time to make sure it was OK to use over the counter Actifed for my allergies.
4) No matter what the laws are in certain locations and no matter what your personal beliefs are, YOU have to decide what's more important to you. If getting high or being in less pain or whatever is your choice, then you can either quit or take your chances with the system. As health conscious as most of these drivers are and considering the contracts and the moral clauses they are subject to, I find it incredulous that ANY driver would use ANY type of product without knowing EXACTLY what was in it and whether it could trigger a positive test or even a false positive. I like the Dinger, but I thought his excuse was as lame as Mayfield's.