In 1987, following implementation of the Washington safety restraint mandatory usage law, collision statistics indicated an increase in motor vehicle crashes where occupants had died while utilizing safety restraints. In order to investigate this issue, a "Fatal Collision Research Team" was established to evaluate and reconstruct collisions where a restrained occupant had died. Collisions were analyzed over a three year period and included 337 crashes involving 1058 occupants of which 446 died.

The team analyzed fatal collisions involving restrained occupants, and documented restraint usage and survivability of the crash. Crash survivability was determined by the Collision Deformation Classification (CDC) which measures the extent of crush or intrusion into the passenger occupant area of the vehicle. The extent of intrusion that would result in survivable or non-survivable collisions was defined separately for front, side, rear, and rollover crashes. The survivability of the crash was determined individually for each occupant and independently of whether the occupant lived or died. In addition, a measure of deceleration forces (Delta V) was used when appropriate for the type of crash and when sufficient data were available.

The major findings were:​ (1) that in the majority of cases where a restrained occupant died, the fatality can be attributed to the extent of vehicle crush and deceleration forces, i.e., the crash forces and dynamics made the crash non-survivable, and (2) restraint misuse seemed not to be a major contributory factor in fatal crash injuries.