theoretical question for fiddletown...
... and no, this isn't referring to me; I'm in a job that requires testing, thanks.
But what if somebody were to go on a trip to someplace like Amsterdam, where marijuana is not only legal but is sold at sidewalk cafes, but then returns to the US and is tested, for whatever reason?
Technically, he hasn't used marijuana in US territory, and hasn't broken any state or federal laws. However, three weeks later... how might this work?