Legal Question in Landlord & Tenant Law in California

Re: Is it legal in CA to make two roommates fully liable for each other's rent?

Why do you think if is unfair or illegal, aside from being her parent and wanting the best for her? I assume they signed the lease together; if effect, they were co-signers for each other. If you co-signed for the car she buys and she stops making her part of the payments but you have paid all you told her [not the car dealer], do you think that ends your economic liability? If you thnk he liability may have ended when she moved out, then you are denying she was a co-signer. The landlord rented one apartment unit to the two of them, not single rooms to each. If he had not made them co-signers then one could tell him that she paid her part of the rent but the other tenant did not, and the other says the same as to your daughter. Is the landlord supposed to figure out who is telling the truth?

You are talking about, apparently, 5 days of rent, or 14% of the month period. Why would the landlord require only a security deposit of 14% of one month's rent? Also, did she give 30 days notice 30 days before moving out or at least 30 days on the date the tenancy expired? You indirectly state that the lease period begins on the first of the month; so if your daughter gave notice on the first of the prior month and he let her stay five days into the following month, making it harder for him to rent to a new tenant, the landlord was being very nice to her. In return for which you want to sue him. And did she ask her roommate if she had paid the rent?

Your daughter obviously has a lot more to learn about life and responsibility.