Illinois Child passenger Safety Protection Act requires children ride rear-facing car seat until the age of two. According to Illinois car seat laws, children under 2 must be secured in a rearfacing child seat unless they meet certain requirements.Illinois car seat laws require children under the age of 8 years to be secured in a child restraint system (car seat). Children under the age of 2 (unless they are 40 pounds or 40 inches tall) must be secured in a rearfacing child restraint system. It's recommended that you continue to use child restraint systems beyond age 8, but Illinois law doesn't require them. Should lie across the upper thighs and be snug across the shoulder and chest to restrain your child safely in a crash. For instance, some states require children to be in a rear-facing car seat until they are at least two years old, while others may have weight-based criteria. 1, 2019, Illinois law requires children under age 2 to be properly secured in a rear-facing child restraint system unless they.