Seat belt legislation describes laws that are put in place to govern and regulate the use of seat belts in automobiles. Such laws determine whether or not an automobile company is required to install seat belts in its vehicles. They also determine whether or not people seated in various parts of an automobile are required to wear a seat belt when the vehicle is in motion. While most western countries do have seat belt legislation of some form, the specific details can vary significantly from nation to nation and, in the US, from state to state. Seat belt legislation does tend to reduce fatalities resulting from automobile accidents in places where such legislation is present and enforced.

Seat belt legislation can vary significantly from location to location, even within a single country. In some states in the US, for instance, the police can pull someone over for not wearing a seat belt while in other states they can only penalize someone for not using a seat belt if they first pull them over for some other violation. In some states, everyone in the car above 16 years of age is required to wear a seat belt while in others only the driver and front-seat passenger must wear a seat belt. The fines for violating seat belt legislation also vary from location to location, though they almost always involve a small fine for first-time offenders. Neglecting to use a seat belt can also reduce the monetary rewards that one can claim from a lawsuit if one is injured in a crash.

Despite the fact that seat belt legislation and use has been shown to reduce fatalities resulting from car crashes, such legislation does have its opponents. The primary arguments against seat belt legislation are based in personal liberty. Many feel that, because seat belt use tends only to affect the individual, the individual should be allowed to choose for himself whether or not to wear a seat belt. Others have pointed out that seat belts can actually cause chest and neck injuries in collisions. Chest injuries from seat belt use can even lead to heart attack or lung bruising.

A phenomenon known as "risk compensation" is another argument used against seat belt legislation and use. Risk compensation is a phenomenon by which people compensate for reduced risk by acting with less caution. In the case of seat belt use, some argue that people who wear seat belts are likely to drive more carelessly than those without seat belts. They believe that they are protected by the seat belt, so they are not as careful with their driving practices.