... because unbuckled passengers in rear seats are nearly eight times as likely to be hurt in a crash and their unbelted bodies can become dangerous projectiles, potentially hurting front-seat passengers.

In a crash, an unbuckled rear-seat passenger can become a human projectile that could hit the front seats and their occupants with a brutal force that could push a driver into the steering wheel with devastating consequences. In such cases, the driver is twice as likely to be killed.

Worse than that is the chance of being ejected from the vehicle. The most common cause of ejection is not wearing a seat belt. Drivers or passengers who fail to wear a seat belt may be thrown forward through the windshield due to the force of the accident. A person can also be ejected through the side window or out a car door during a serious crash.