In nearly every state in the nation, it's illegal to drive without a seat belt. Seat belts save lives, that is proven. Some disagree with seatbelt laws, but regardless of your view, they are in effect nearly everywhere. A recent study of the death of police officers found that more than 80% of offices who were killed in an auto crash were not wearing their seatbelt at the time. Many people don’t wear seatbelt because there are to restrictive. Police officers don’t like to wear them because it slows their movements in and out of their vehicles following an arrest or incident. Wearing seatbelts saves lives and that’s all there is to it.
It is, however, not legal in many areas for a police officer to pull you over and give you a ticket based solely on you not wearing a seat belt. In many parts of the country, a police officer cannot pull you over for not wearing a seat belt, but can give you a ticket for not wearing one in conjunction with another traffic violation (speeding, missing a stop sign, etc).
In many areas, passengers who are not wearing a seat belt can also be issued tickets. In other areas, those passengers are the driver's responsibility and their lack of seat belt use means another ticket for the driver. It pays be aware of the laws in your area.
Traffic violations are common and paying traffic ticket fines is not fun. When the mandatory seat belt fine is added to that, though, it's only worse. So for your own safety and to save yourself the added headache of a tack-on ticket, wear your seat belt at all times.