There are many ways that a landlord can constructively evict a tenant. One way is for the landlord to commit a ”material breach” of the lease. Under California law, a landlord is required to provide basics in a rented apartment like security, heat and water in exchange for rent. If the landlord substantially fails to provide these things or interferes with the tenant’s beneficial enjoyment of living in her apartment, then the tenant can move without notice and sue.
Courts have held that in these situations the tenant is not required to give notice to the landlord. In other words, if the landlord is so interfering with the tenant’s right to live in the apartment because of a failure to make basic repairs or provide heat, then the tenant can move out without giving the landlord notice or time to fix the problem.
As a practical matter, I counsel tenants to send a letter (not an e-mail) to the landlord stating exactly what the problem is and asking when it will be fixed. If the landlord ignores the letter or makes inadequate repairs, you might have grounds for arguing you have been constructively evicted.