Production seats and specially designed research seats were analyzed with respect to seat-safety belt interaction under frontal crash conditions. The objective was to evaluate seat influences on effectiveness of safety belts, or any other restraint system. We determined that classical measurement techniques alone are insufficient to completely cover problems of seat-safety belt interaction. Supplementary evaluation parameters of dummy kinematics were therefore defined to clarify the poor safety design of current production seats necessary seat design development for increased safety. Proposals for possible effective seat design were then derived to satisfy necessary new safety requirements for seating.