If your child is under the minimum age/weight standards set by the state of California, you are required to supply an approved car seat for each child that the law applies to. It is the responsibility of the parent or guardian traveling with the child to make sure that the child is in compliance with the California Child Passenger Restraint Requirements.

Note that the California law changed on January 1, 2002. 

Effective January 1, 2002

(Excerpts from the California Vehicle Code)

27360.

(a) No parent or legal guardian, when present in a motor vehicle, as defined in Section 27315, shall permit his or her child or ward to be transported upon a highway in the motor vehicle without providing and properly securing the child or ward, in a child passenger restraint system meeting applicable federal motor vehicle safety standards unless the child or ward is at least one of the following:

(2) Weighs 60 pounds or more.

(b) No driver shall transport on a highway any child in a motor vehicle, as defined in Section 27315, without providing and properly securing the child in a child passenger restraint system meeting applicable federal motor vehicle safety standards unless the child is at least one of the following:

(1) Six years of age or older.

(2) Weighs 60 pounds or more.