In California, if you do not have an Advance Directive and cannot communicate your wishes, there is no standard procedure for someone else to decide for you. The rules can also apply to minors, certain types of treatment, or pregnant women. While some states allow for a verbal appointment of a decision-maker, this information is focused on planning for situations where you cannot make decisions for yourself and does not cover verbal appointments.
Source: CDSS – Your Right To Make Decisions About Medical Treatment