There are many laws for car seats in this country, and all of them were put in place to make sure that our children stay safe in vehicles. To keep your child safe and to stay out of trouble, you should take the time to familiarize yourself with these laws. They do vary from state to state, so you should also make sure you are reading those that are relevant to where you live.
Many laws for car seats have to do with the size of the child. While there are some laws that have to do with the age of a child, height and weight are often more important. Since children develop at different rates, you need to be sure that your child stays safe according to their development, not their age.
Make sure you find out what the laws for car seats say about when your child can be moved to a forward facing car seat. Also see when they can be moved from a car seat to a booster seat, and then safely to the car seat and seatbelt. By reading up on these you will be doing everything you can to keep your child safe in the event of an accident.