True, it depends on what you're doing. If you have a security clearance (which, importantly, is not true for all federal employees) then you are in a drug testing position. Otherwise, it depends on what you're working on/with. Like many jobs involving heavy machinery, wage grade employees without clearances are going to get drug tested, while a clerk in an office probably won't be in a drug testing position. Finance stuff? Probably a drug testing position, whether with a clearance or not.