California Code, Insurance Code - INS § 1616

Before any nonadmitted foreign or alien insurer shall file or cause to be filed any pleading in any action, suit or proceeding instituted against it, the insurer shall either (1) procure a certificate of authority to transact insurance in this state;  or (2) give a bond in the action, suit or proceeding in an amount to be fixed by the court sufficient to secure the payment of any final judgment which may be rendered in the action, suit, or proceeding.