THE TOYOTA PRIUS 2006 WAS HIT FROM BEHIND (REAR ENDED) ON 05/13/2021 AND DRIVER'S SEAT COLLAPSED BACKWARDS, CAUSING A HEAD INJURY. THIS WAS NOT EXPECTED AND IS NOT ACCEPTABLE BY ANY SAFETY STANDARD. FORTUNATELY THERE WERE NO OTHER OCCUPANTS IN THE VEHICLE. THIS WAS A CHAIN COLLISION AND THE PRIUS WAS STATIONARY WHEN IT WAS HIT IN A SECONDARY COLLISION AND STILL THIS HAPPENED, WHAT IF OUR CAR WAS HIT IN THE PRIMARY COLLISION OR WHAT IF THERE WAS A CHILD ON THE BACK SEAT?! THE VEHICLE IMMEDIATELY BEHIND WAS ALSO STATIONARY BEFORE IT EXPERIENCED THE FIRST ORDER COLLISION. THESE SEATS DESERVE A SAFETY RECALL. ONE CAN FIND MANY OTHER SEAT COLLAPSING EVENTS, EVEN WITH CHILDREN KILLED OR BRAIN DAMAGED ON BACK SEATS. PLACE OF THE ACCIDENT: THE CHESAPEAKE EXPRESSWAY (168). ACCIDENT REPORT ATTACHED.