2007 California Labor Code Chapter 4. Trains

CA Codes (lab:7000)

7000.  As used in this section "caboose" means a caboose forming a
part of a train and occupied by employees or caretakers, or both.
   If conditions warrant it for the safety of the occupants of a
caboose the conductor, in using a pusher engine, may place it ahead
of the caboose.
   This section applies only to main line movements of over five
miles.
   This section shall not prevent the use of an electric locomotive
at the rear of any train.
   This section shall not apply in any case of casualty, unavoidable
accident, or act of God; nor under circumstances which are the result
of a cause not known to, and which could not have been foreseen by,
the railroad corporation, or its officer or agent in charge of a
train.  This section shall not apply to the operation of wrecking, or
relief trains.