Final answer:
When charged with DWI, one must usually undergo a Breathalyzer test, which assesses blood alcohol content by analyzing breath. Additionally, a Field Sobriety Test, including various coordination tasks like walking or balance tests, may also be administered. These are used to evaluate whether an individual is under the influence of alcohol.
Step-by-step explanation:
If charged with DWI (Driving While Intoxicated), individuals typically must undergo a Breathalyzer test to measure blood alcohol content (BAC). This test estimates the alcohol concentration in the bloodstream by analyzing the alcohol content in the breath. The Breathalyzer device functions by oxidizing ethanol in the breath, where the chemical reaction involves converting ethanol to acetic acid, changing the solution color from yellow-orange to green. This color change correlates with the level of alcohol in a person's breath, and thereby their blood.
Another part of assessing alcohol influence is the Field Sobriety Test (FST), which is a physical coordination exam conducted by law enforcement. This test includes tasks that depend on the cerebellum, a brain region sensitive to ethanol and crucial for coordinated movements. The FST can involve walking in a straight line, standing on one leg, or horizontal gaze nystagmus (an eye test), which are designed to reveal impairment in balanced coordination likely caused by alcohol consumption.
In many jurisdictions, a BAC level of 0.08% is considered legally impaired for operating a vehicle. The outcomes of these tests are pivotal in determining whether someone has violated DWI laws.