When functioning properly, and worn properly, seat belts can save lives. When seat belts malfunction they can kill you, even in an accident that would have otherwise caused minor injuries or no injuries at all. Unfortunately, in most states, the law requires that you wear one whether it is defective or not.

Common Malfunctions
Retractor failure. Just a tiny amount of slack in a seat belt will cause very serious injuries. During an accident, the retractor mechanism locks, keeping the seat belt from feeding out, so it will remain snug. When the retractor fails to lock it allows slack to be created in the belt.

Internal unlatching. Certain types of buckles, those with the latch on the front of the buckle, can come unlatched when there is an impact to the back of the buckle. This can happen in crashes with low forces.

Protruding release button. A release button that sticks out from the buckle can be pressed by a gentle bump, under normal driving conditions, even when there is no accident. When this happens the belt does not always come apart enough for passengers to be aware that they are no longer protected, but obviously, will not hold in the event of a crash. Chrysler installed Generation Three (Gen 3) buckles, which have the protruding release button, in about 14 million vehicles from 1993 to 2002.

Design defects
Some seat belts function properly when worn properly, but are designed in a way that makes them so likely to be work in an unsafe manner, that they are still considered defective.

Automatic belts. May cars are equipped with a shoulder strap that automatically moves into place when you get in and close the door. The idea is to make sure that you are wearing your seat belt, even if you forget and whether you really want to or not. The problem with this is that wearing only the shoulder strap without a lap belt is far more dangerous than wearing no seat belt at all. All of the force of the accident goes to the neck or head, causing neck injuries, spinal cord injuries, brain injuries, and even death. Door mounted automatic belts can cause ejection from the vehicle if the door comes open during a crash.

Window shade device. The window shade device was created to give drivers and passengers freedom of movement, when they need it. It allows you to create slack in the belt, so you can easily turn around in your seat or bend forward. The slack stays in the belt until you give a quick tug which activates the retractor and pulls the belts snug. The problem with this device is that most people don’t know they need to tug on the belt. Some even think that it is meant to provide more comfort while riding in the vehicle.

Misleading evidence
Seat belt failure gives the misleading appearance that you were not wearing a seat belt during an accident.