One of my Facebook friends has just asked on fb if it is legal for her 7 year old to have the back taken of her boost seat. I am now concerned I have been putting my children at risk by not having backs on their booster seats. My 7 year old has been to tall for quite a while to have the back on, so just sits on the base (I think this is called a booster cushion?). But my nearly 5 year old boy who does still fit in his seat with the back on, sometimes just has a booster cushion when in our second car or out with his grandparents. I am getting conflicting advice from different Internet sites, so wondering if anyone can help me. Thank you.