Children under the age of 8 are required to be secured in a car or booster seat. Under CA law, children must be restrained in a child safety seat until age 8 or until they reach a height of 4 feet 9 inches.Families that meet the income requirements and complete the class will receive a free car seat. Clinic in the Park's Boosters in a Bag. A complete listing of child car seat inspection stations go to the NHTSA website here. California law only requires those 8 and under to ride in back seat. The 10 year old can legally ride in the front. Children under 2 years of age shall ride in a rear- facing car seat unless the child weighs 40 or more pounds OR is 40 or more inches tall. By law, all U.S. states require child safety seats for infants and children. If they're between ages 1 and 3 and weigh more than 20 pounds, children still have to be in a child restraint.