procedure for filing for joint child custody in CA

This is not a question that can be answered in a forum such as this. It is far too complicated and requires an analysis of a myriad of facts. You really need to consult with an attorney who practices in this area (Family Law - custody). You should search the Internet for such an attorney who is local to you and call and ask if you can have an initial consultation on this subject. Many attorneys provide free initial consultations. Good luck with this matter.

Counsel is corrrect. You are best served by hiring a competant attorney. It also depends what you mean by joint custody. If cannot afford an attorney Los Angeles Superior Court has a self help center on the 4th floor of the courthouse. Also view the LASC web site and my web site www.la-familylaw.com for more information

While I agree with previous responders, I might add that if there was no court proceeding to establish custody but it exists because other parent has kept the child and is not permitting any contact, you must file a "Complaint to Establish Paternity" (assuming you were never married) with a Summons, along with an Order to Show Cause requesting custody, which will give you a hearing date to appear before the court. You can file in your 'district' court, or as previously mentioned, in the main courthouse located at 111 N Hill Street. and there is a self-help center on the 4th Floor in the Clerk's Filing Room (near the Grand Street entrance) to help you with completing the forms and explaining how to serve the other side with copies if you can't afford an attorney.
Law Office of Judith A. Routledge