2009 California Welfare and Institutions Code - Section 1500 :: Part 2. Minors Crossing The Mexican Border

1500.  A peace officer of any city or county shall prevent the entry
from California into the Republic of Mexico at the border by any
resident of this state under the age of 18 years who is unaccompanied
by a parent or guardian or who does not have written consent for
such entry from a parent or guardian or who does not have a passport.
The authority of the peace officer under this part shall be only to
prevent entry and not otherwise to detain. Nothing in this part shall
be construed to limit the authority of a peace officer under any
other law of this state.