If you are on a separate lease, you would seem to only be subject to eviction if you breached your own lease in  some way--in the example you gave, such as by yourself using drugs, or at least being an accomplice in the others' drug use. When tenants are on seperate leases, the eviction of one does not necessarily lead to or trigger the eviction of another; each tenant is only evictable if he or she does something which would personally lead to his or her eviction. In this case, the landlord may believe you were involved in the drug use; he or she would have to establish that in court, if you refuse to leave and the landlord takes you to court for the eviction. The standard of proof in an eviction proceeding is "preponderance of the evidence," or "more likely than not"--that is, drug use would not have to be shown beyond a reasonable doubt, but rather to a lesser standard of proof.Note that you would not be legally bound to inform the landlord of other tenant's drug use except perhaps if the lease itself contained some obligation to do so.You would be well advised to consult in person with a landlord-tenant attorney about your situation.