In Idaho, illegal drugs is a basis for eviction. It does not affect the security deposit. You are not entitled to it because it isn't your money. The landlord may be able to keep it to compensate the landlord for expenses, etc. However, since you are still there, I imagine that the landlord will have to return the deposit to your roommate and make you come up with his share.
Answered on Dec 12th, 2013 at 6:51 PM