Legal Question in Real Estate Law in California

A very difficult situation. You have basically three choices: the police, the courts, or self-help. I think the police non-response was perhaps off base, because "technically he lives here" is not a reason; a lodger or guest, once told to leave, becomes a trespasser. However, the police are too busy with dangerous people and other emergencies, and would rather not devote officer time to matters that may clear up on their own.

A 30-day pay or quit notice is appropriate for tenants or subtenants, but if I understand correctly, this person has never agreed to pay anything, nor to perform services instead of paying. Therefore, I'd say a 30-day notice was unnecessary. The guest (or lodger) can be told to leave, maybe not immediately this second, but I'd say at the earliest opportunity, like this weekend. I'd give a written notice, but give maybe seven days, specifying in the notice that he was a guest or lodger, that siad status is terminated, and that he is to leave at the earliest possible time, with all belongings.

You should probably advise the landlord what's going on, depending upon your relationship with him/her/it, and ask for appropriate assistance.

You can also go to court, preferably with the assistance of a local lawyer, and ask for a restraining order -- not the only possible court proceeding, but perhaps the quickest. There are two possible routes: under Code of Civil Procedure section 527 if the request is for a TRO along with a suit for some kind of permanent relief; or under CCP 527.6 for a restraining order where there is a credible threat of harassment or violence.