I OWN A 2006 PRIUS WHICH I WAS DRIVING AT LOW SPEED IN A LEFT TURN BEHIND A FREIGHT TRUCK. AS I APPROACHED THE REAR OF THE TRUCK I APPLIED THE BRAKE. THE BRAKE PEDAL DEPRESSED IN THE NORMAL FASHION, HOWEVER, THERE WAS NO RESPONSE FROM THE VEHICLE -- IT CONTINUED TO MOVE FORWARD WITH NO CHANGE IN SPEED. IMMEDIATELY AWARE THAT SOMETHING WAS WRONG, I QUICKLY AND METHODICALLY 1) VISUALLY CONFIRMED THAT MY FOOT WAS ON THE BRAKE AND THAT THERE WAS NOTHING OBSTRUCTING THE PEDAL, 2) CHECKED MY PERIPHERAL VISION TO CONFIRM THAT I WAS INDEED MOVING FORWARD RATHER THAN THE TRUCK AHEAD OF ME MOVING BACKWARD AND 3) PLACED BOTH FEET ON THE BRAKE AT FULL FORCE AND HELD FIRM WHILE QUICKLY VISUALLY CHECKING THAT MY FEET WERE IN FACT ON THE BRAKE. I ALSO CHECKED THE DASHBOARD TO CONFIRM THAT THE CAR WAS ON AND IN A NORMAL "DRIVE" GEAR. AT LAST, IT WAS TOO LATE AND I SMASHED INTO THE BACK OF THE TRUCK, STILL WITH BOTH FEET ON THE BRAKE. THE TRUCK DRIVER EMERGED FROM THE CAB, A BIT SHAKEN BUT NOT HURT. HIS TRUCK WAS NOT HARMED AS I HIT A HEAVY METAL FRAME THAT WAS ATTACHED TO THE BACK OF THE TRUCK. THE HOOD OF MY CAR WAS DENTED AND SCRAPED. IN RESPONSE, I REMOVED THE CAR FROM TRAFFIC, CANCELLED THE MEETING I WAS ON THE WAY TO AND SLOWLY DROVE A VERY SHORT DISTANCE TO MY EMPLOYER'S PARKING LOT AND PARKED THE CAR. I CALLED THE NEAREST TOYOTA DEALER, EXPLAINED THAT THE BRAKES FAILED AND, AT THE DEALERS RECOMMENDATION, CALLED THEIR TOWING SERVICE TO TAKE THE CAR TO THEIR SERVICE DEPARTMENT