What is the most accurate way to determine if a person was wearing a seat belt?

The most accurate way to determine if a person was wearing a seat belt is to look for physical evidence, such as bruising. This method provides tangible evidence that can indicate whether a seat belt was in use during an accident. For instance, a person who is wearing a seat belt may have specific patterns of bruising that correspond to the points of contact with the seat belt, which typically occur in the shoulder, across the lap, and on the chest.

Other methods, such as asking a witness or checking the vehicle's safety features, might not provide a definitive answer. Witness accounts can be unreliable due to the stress of the event, while examining the seat belt for marks may only indicate if it was engaged but not reliably confirm its usage during the incident. These methods lack the direct physical evidence that bruising would provide, making them less accurate than examining injury patterns on the individual.

Therefore, looking for physical evidence, such as bruising, is the most reliable way to ascertain seat belt usage in an investigation.