A seat having a seat frame with a seat back designed to prevent injuries to a rear occupant seated behind the seat as the rear occupant moves forward into the seat back during a frontal crash of a vehicle, the seat including a seat back frame part designed to support the back of any occupant but which can rotate during a crash as a rear occupant moves forward into the seat back, the invention including at least one energy absorbing assembly to control the rotary motion of the rotating seat frame part, the rotating frame part maintained in a non-rotating state by an articulating or breakable pin which when moved or broken permits the frame part to rotate as the rear occupant engages the seat frame in response to a frontal vehicular crash.