When I’ve run into this situation, it has been for subjects which have smoked marijuana regularly for years while working for a company for years without incident. All of the sudden the company gets a government contract which requires that the subject have a public trust background investigation and the subject doesn’t really understand what is changing or why they can’t continue to use pot. Most have been in the IT field and I assume they had no problem getting a new job with a company that does not have government contracts after their public trust was (presumably) denied because they said they planned to continue to use.