Which device is commonly used to assess a driver's BAC?

The device commonly used to assess a driver’s Blood Alcohol Concentration (BAC) is the Breathalyzer. This handheld device measures the amount of alcohol in a person’s breath, which is then used to estimate their BAC. Breathalyzers are widely used by law enforcement during traffic stops to quickly determine whether a driver may be under the influence of alcohol.

While field sobriety tests are used to evaluate a driver's physical and cognitive abilities, they do not provide a specific measure of BAC. Urine tests and blood tests can also assess BAC, but they are generally used in more controlled settings or for more comprehensive testing, making the Breathalyzer the most common device for immediate roadside assessments by officers.