Legal Question in Landlord & Tenant Law in California

The rationale for a mutual thirty day notice is to give adequate time for the tenant to find a new place and the landlord to find a new renter so there is no loss of rent. If he found someone, he would have told them they can not move in until X date [and they may have had to give thirty days notice to their landlord so they can not move before X date], so your leaving early than 30 days does not help the landlord. He has an empty unit because you did not give an accurate move out date. Is it fair that he losses money because of your error?

The law is clear that he is entitled to a full month's rent. If you did not pay all the rent that is due, he is entitled to get the balance out of the security deposit. You do not say directly, but apparently you failed to comply with the rental contract by not paying for the full thirty days and trying to use the security deposit to cover the last month of rent. That is in breach of the contract and you could have been with a three day notice to pay or leave.

Was the unsafe behavior of another tenant a breach of the implied peaceful enjoyment of the premises? probably not. If you had not paid the full rent, you were already in breach of the contract so the landlord might have no duties to you except those mandated by law. You have not given any information that the landlord had any ability to control the other tenant or prevent the unsafe condition. Even if he was given a three day notice immediately upon the unsafe act, with the delays inherent in eviction for a three day notice, your thirty days would have been up before the landlord could have legally removed him.

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