OUR PARKING PAWL MAYBE DEFECTIVE. WE ALWAYS ENGAGE OUR EMERGENCY BRAKE WHEN PARKING IN OUR DRIVEWAY; TODAY WAS NO DIFFERENT, BUT WHEN I ATTEMPTED TO RE-ENTER MY CAR IT STARTED ROLLING BACK BY ITSELF EVEN WITH THE EMERGENCY BRAKE ENGAGED. I TRIED TO STOP THE CAR FROM ROLLING BACK OUT OF MY DRIVEWAY IN FEAR FOR MY 2 YOUNG CHILDREN STILL IN THE CAR. IN THAT ATTEMPT, I ENDED UP BREAKING MY HAND AND HAD TO GO THE THE ER. EVENTS: 1. PULLED UP INTO DRIVEWAY AND STOPPED COMPLETELY 2. ENGAGED EMERGENCY BRAKE 3. PUT SHIFTER IN PARK POSITION 4. STEPPED OUT TO OPEN GARAGE 5. ATTEMPTED TO RE-ENTER VEHICLE 6. IT STARTED TO ROLL BACK 7. I TRIED TO KEEP IT FROM ROLLING BACK