California Code, Penal Code - PEN § 647a

(a) Any peace officer, as defined in subdivision (a) of Section 830.1 or Section 830.31, 830.32, or 830.33, may transport any person, as quickly as is feasible, to the nearest homeless shelter, or any runaway youth or youth in crisis to the nearest runaway shelter, if the officer inquires whether the person desires the transportation, and the person does not object to the transportation.  Any officer exercising due care and precaution shall not be liable for any damages or injury incurred during transportation.

(b) Notwithstanding any other provision of law, this section shall become operative in a county only if the board of supervisors adopts the provisions of this section by ordinance.  The ordinance shall include a provision requiring peace officers to determine the availability of space at the nearest homeless or runaway shelter prior to transporting any person.