googling "CA good samaritan law" brings up lots and lots of links.
One of them takes you to this.
* "Good Samaritan Law," passed by California in 1959
o No legal obligation to provide aid
o Immunity from malpractice suit if aid is provided
o Applies to outside of hospitals only
o Withdrawal of legal immunity if payment accepted
Copyright 2001 by the University of Florida
Since I am not driving in CA, I am not going to pursue it further other than to say that I found recent discussions by lawyers of the CA good samaritan law in which it was pointed out that you are not protected by CA law if you engage in any attempted life saving activity in which you have not had training.
For instance, if you gave CPR and caused injury, you are not protected in CA.
NC specifically states that you are protected so long as you acted reasonably.
It appears that CA law is written only to protect those who are EMC, medical or other trained emergency workers.
So a blanket statement that you are required to stop and render assistance could cause someone to get in legal doo-doo, if they followed that advice.
Therefore, asking for a link is not off the wall.
If you want a real eye opener, try this:
http://firstaid.about.com/od/medicallegal/Legal_and_Liability_Issues_Related_to_Rescue_and_First_Aid.htm
See post 513.