What happens if you take a drug test and end up with a positive result, but you never took any drugs? Can you convince the FAA not to revoke all of your certificates if you tell them you don’t know how the drug metabolites ended up in your drug test result? This so-called “unknowing ingestion” affirmative defense has been tried, but, unfortunately, with little success. For a discussion of a recent NTSB decision analyzing this very situation, please read my latest article on the topic: Unknown Or Inadvertent Ingestion: An Unconvincing Affirmative Defense To A Positive Drug Test Result.