A study by the Centers for Disease Control and Prevention examining self-reported seatbelt use in jurisdictions with primary versus secondary enforcement across the United States revealed that, whilst in general self-reported seatbelt use increased over the study period of 2002 to 2010, jurisdictions with primary enforcement laws had significantly higher seatbelt use than jurisdictions with secondary enforcement laws  (89% vs. 80%).

The distinction between primary and secondary enforcement may require an explanation for those outside of the US. Primary enforcement seatbelt laws mean that Police can stop a vehicle if they see someone not wearing a seatbelt, and the relevant citation can then be issued. Secondary seatbelt laws allow the Police to only issue citations for not wearing a seatbelt after stopping the vehicle for a different driving offence (such as speeding). Thirty-two US states had primary seatbelt laws at July 2012.

www.sciencedirect.com/science/article/pii/S0022437512000977

Seatbelts play a crucial role in reducing injury in the event of a motor vehicle crash, and in many instances they may be the difference between life and death. Seatbelts are particularly important for the smallest occupants, children, with a 54% – 71% reduction in fatal injury for the youngest passengers.

Other jurisdictions such as the state of Queensland in Australia have legislation protecting our youngest passengers, with mandatory child seats (such as boosters) required for children under the age of seven. After the age of seven, parents are able to seat their child in an adult seatbelt, however the size of the child (height in particular) requires consideration also. For example, my son – one of the smallest in his grade – progressed to an adult seatbelt only at age 11. Such individual differences highlight the difficulties with legislation based on an age-related criterion.