Can I use Marijuana if I have a Security Clearance?

There is a lot of confusion about marijuana use while possessing a clearance now that a number of states have legalized recreational use of the substance.  Marijuana use, however, remains illegal at the federal level.  While a small amount of recreational use prior to applying for a clearance may be mitigated by legality at the state level or medical purposes, marijuana remains a controlled substance and its use is prohibited while possessing a clearance.  Testing positive on a urinalysis test or an arrest for possession of marijuana is not a required indicator of use – the SF-86 requires the disclosure of controlled substances and/or misuse of prescription medications during the last seven (7) years. This includes the use of both THC-8 and THC-9, regardless of its legality in any particular state.