Keeping the druggie money

[Tim Johnson]

Hi BP!

My wife and I purchased an 18 unit multifamily in December.  The building is full of mostly great people, but there was one fellow that always smelled like pot.  We talked to him about it but the odors continued.

He was on a month-to-month lease.  We told him we had decided not to renew his lease (because we really don't want druggies living there).  He moved out last night.  When my wife was inspecting the place she found a small baggie of pot.  

The previous owners had everyone sign a "Anti-drug lease addendum".  In that document it says that if they are are found with drugs they lose their security deposit.  

Does anyone know if this violates any kind of renters rights to take away his security deposit as more of a punitive measure than a recovery of actual loss?  He signed the anti-drug document. and I'm happy to keep the money.  But I want to make sure I won't violate his rights and/or get in trouble.