Eleven case investigations of the severe to fatal (AIS 4 to 6) injuries sustained by young children (two weeks to 2 years) in FMVSS 213 certified child seats, during foreseeable accidents and circumstances, are described in some detail. Using the analytical protocol of SAE #890382 (Live Subject Safety Research), head injuries to the involved infants and children were duplicated and the injury reduction effects of simple and inexpensive child seat modifications were demonstrated. The conclusions are as follows:​ the forces to a child’s head through child seat head surfaces are not limited when contacting an intruding vehicle interior, although such energy absorption protection could be provided at little additional cost. Furthermore, child seats designed for infants “up to 20 pounds” are unsafe for newborn infants.