What is the primary purpose of the Preliminary Breath Test (PBT)?

The primary purpose of the Preliminary Breath Test (PBT) is to demonstrate the association of alcohol with observable impairment. This instrument serves as an initial screening tool during a traffic stop to help law enforcement officers determine whether a driver has consumed alcohol and to what extent this consumption is associated with observable behaviors or signs of impairment. In this context, the PBT offers officers a quick and non-invasive way to assess whether further testing, such as a more accurate breath or blood test, is warranted.

The association with observable impairment is critical because it helps officers make informed decisions about the driver's ability to operate a vehicle safely. While the PBT indirectly provides insight into blood alcohol content (BAC) levels, its main role is not to measure BAC directly, but rather to support observations of a driver's ability to function and respond appropriately to driving conditions. Other options, such as assessing a subject's physical condition or evaluating the effects of different alcohol types, fall outside the primary function of the PBT.