TL*THE CONTACT OWNS A 2000 ACURA INTEGRA. WHILE THE CONTACT'S VEHICLE WAS AT A COMPLETE STOP, IT WAS REAR ENDED BY ANOTHER VEHICLE TRAVELING 50 MPH. SHE STATED THAT HER SEAT BELT LOCK SYSTEM FAILED, WHICH CAUSED THE SHOULDER BELT NOT TO RESTRAIN. THE LAP BELT WAS THE ONLY PART THAT PROPERLY RESTRAINED. THE CONTACT SUFFERED A CONCUSSION DUE TO HER HEAD STRIKING THE STEERING WHEEL. THE INSURANCE COMPANY HAS NOT DECLARED IF THE SEAT BELT WILL BE INVESTIGATED. THE VEHICLE WAS DESTROYED. CALIFORNIA HIGHWAY PATROL FILED REPORT NUMBER 9550. THE POWERTRAIN WAS UNKNOWN. THE CURRENT AND FAILURE MILEAGES WERE 73,000.