Types of Field Sobriety and BAC Tests

Driving while drunk or intoxicated is against the law in all 50 states. Most states have set a legal threshold determining when a driver is too drunk to drive. This threshold is in terms of blood alcohol concentration (BAC), or the amount of alcohol in a driver’s bloodstream. Law enforcement officers may use other means of testing for intoxication as well, such as field sobriety tests. If a driver fails a sobriety test in Arizona, he or she could face a driving under the influence (DUI) charge.

Field Sobriety Tests

A field sobriety test is something law enforcement officers in Arizona can use to gauge a driver’s level of drunkenness or drug impairment. It can refer to a few different types of physical tests designed to check the driver’s ability to move, balance, talk and follow directions. The National Highway Traffic Safety Administration currently approves three field sobriety tests. Each check for a different type of reflex alcohol can affect.

  • One-legged stand test. The suspect must stand with one leg hovering about 6 inches off of the ground, with the toe pointed, and count to 30. The driver’s arms should remain at his or her sides. An officer will look for the driver dropping the foot down, swaying, hopping or using the arms to maintain balance.
  • Walk-and-turn test. The suspect must walk in a straight line while keeping his or her feet touching, heel to toe. On the ninth step, the suspect must turn and go back the other direction. The suspect may fail if he or she does not follow the instructions, cannot touch toe to heel or loses balance.
  • Horizontal gaze nystagmus test. The suspect will need to follow a small object with his or her eyes while keeping the head still. The officer will look for eyes that jerk or bounce, eyes that do not have equal pupil sizes, and eyes with resting nystagmus. Failing four of six requirements could lead to a DUI charge.

Failing a field sobriety test could serve as evidence during a DUI criminal case in Arizona. However, a Glendale DUI lawyer may be able to argue the validity of the test. Video evidence from the police officer’s body or dashboard camera of the field sobriety test, for example, could show the suspect actually passed the test.

BAC Tests

Blood alcohol concentration tests are more reliable than field sobriety tests. They use science to determine a driver’s level of drunkenness. A BAC test can analyze the ratio of blood to alcohol through tests of the breath, blood and/or urine. The Breathalyzer test is the most common during traffic stops. An officer uses a portable device to measure the amount of alcohol in the driver’s breath. If the test reads 0.08% BAC or higher, the officer could arrest the driver for suspected DUI. At the police station, the driver may also have to consent to a blood or urine test. The prosecution could then use the results of the chemical tests as evidence during a DUI case.

Can You Refuse to Take a BAC Test?

As a driver in Arizona, you do not have to comply with a field sobriety test. No law requires drivers to agree to these tests during traffic stops. You can politely decline to take a field sobriety test if a police officer stops you for suspected drunk driving. These tests can be subjective and have inaccurate results. Factors such as injuries and disabilities could lead to failed tests even if the driver is sober.

Most DUI lawyers recommend refusing field sobriety tests. You cannot, however, refuse to take a BAC test during a traffic stop in Arizona without facing legal consequences. When you acquire a driver’s license in Arizona, you agree to comply with chemical drug and alcohol tests. Refusal to take a BAC test can automatically lead to driver’s license suspension, even if the courts do not convict you of DUI. Contact a DUI attorney for tailored legal advice about refusing or failing a drunk driving test in Arizona.