What type of test uses a device to measure the amount of alcohol in a person's breath?

The breathalyzer test is specifically designed to measure the concentration of alcohol in a person's breath. It operates on the principle that the amount of alcohol in a person's breath correlates to the amount present in their blood. When a person exhales into the device, it analyzes the breath sample and provides a numerical value representing the blood alcohol concentration (BAC). This quick and non-invasive test is commonly used by law enforcement during DUI stops to assess whether a driver is impaired by alcohol.

In contrast, the nystagmus test evaluates eye movement and can indicate intoxication by checking for involuntary jerking movements of the eyes. Urine analysis and blood tests are other methods for detecting alcohol levels, but they do not use breath samples; urine tests detect substances in the urinary system, while blood tests require a sample of blood to be drawn and analyzed. Therefore, the breathalyzer test is the appropriate method for measuring alcohol in breath.