You've probably seen the billboards with the line-up of car seats and boosters, like the one pictured above, asking if your child is in the right one. As a father of four small children, I have seen the billboards but didn't go to the website until recently.
Although most parents are aware their baby cannot be put in a forward facing carseat until thiey are one year old and at least 20 pounds, the area seems to get a little fuzzy when it comes to switching from a car seat to a booster seat. The law itself is slightly ambiguous as it says a child may move into a booster at "about 4 years old and 40 lbs." That "about" leaves some room for interpretation. To add to the confusion, I noticed recently on our Graco booster that it says a child "must be approximately 3 to 10 years of age and weigh between 30 to 100 lbs." My worry is that parents will read this and assume that their three year old is ready for a booster because she weighs 30 pounds.
As a Utah personal injury attorney, some of the most heart-breaking cases I have handled involve injuries to children who were in the wrong car seat or booster. I imagine that when a parent moves their child up to a booster before they are ready, it is for convenience's sake, but I would hope that parents would take a more cautious approach. Accidents happen everyday and seatbelts and car seats save lives if used properly. When it comes down to it, small children are safer in a five-point harness until they are big enough and responsible enough to be in a booster.
The same goes for older children. They should be in a booster until they are at least age 8 or 5'7" and are responsible enough to keep their seatbelt on their shoulder.