<Ul> <Li> Case - control studies based on voluntary use of safety aids can attribute to the aid benefits that actually come from the risk - averse nature of those likely to use them voluntarily (confounding), particularly early adopters . </Li> <Li> Fatality rates are subject to considerable stochastic noise, and comparison of single years or short periods can be misleading . </Li> </Ul> <Li> Case - control studies based on voluntary use of safety aids can attribute to the aid benefits that actually come from the risk - averse nature of those likely to use them voluntarily (confounding), particularly early adopters . </Li> <Li> Fatality rates are subject to considerable stochastic noise, and comparison of single years or short periods can be misleading . </Li> <P> Opponents have objected to the laws on libertarian principles . Some do so on the grounds that seat belt laws infringe on their civil liberties . They argue that not wearing seat belts is a victimless crime as the only person harmed is the one making that decision for himself about his own life . </P>

What year did you have to wear a seatbelt