Can you prohibit your tenants from smoking in your rental units?

Effective January 1, 2012, California Civil Code 1947.5 provides that a landlord has the right to prohibit the smoking of tobacco products in all or part of a residential property. This right applies to new tenants who enter into leases after January 1, 2012.  

For existing tenants, a new smoking restriction constitutes a change in terms of tenancy and must be made in compliance with all state and local laws. For specific details read civil code 1947.5