Unfortunately, the housing authority can tell you this--and, in fact, is required to do so. Pursuant to the statutes and regulations under which they get support or grants from the federal government, which support then subsidizes the public housing, they are obligated to use leases which make it grounds for termination to use illegal or controlled substances.I am not aware of any cases which deal with the issue of medical marijuana--that is, whether, if it is legal in the state for that tenant with a prescription, etc., that takes it off the list of proscribed substances that will cause eviction. However, since the federal government has generally not been friendly to the idea of medical marijuana, and federal law still criminalizes marijuana, it may well be that even medical marijuana would run afoul of that lease term. You should consult with an attorney with landlord-tenant experience in your area (if you can't afford one, try legal aid or legal services)--you may be presenting a new question of law which needs to be decided.