Understanding and Challenging Field Sobriety Tests in Arizona DUI Cases

Field sobriety tests (FSTs) are commonly used by law enforcement in Arizona to determine whether a driver is impaired. However, these tests are not foolproof, and their results can often be challenged in court. If you have been subjected to a field sobriety test during a DUI stop, understanding how these tests work and the factors that can impact their reliability is crucial to mounting a strong defense.

Types of Field Sobriety Tests

The National Highway Traffic Safety Administration (NHTSA) has standardized three main field sobriety tests that officers commonly use in Arizona DUI stops:

1. Walk-and-Turn Test – This test requires a driver to take nine heel-to-toe steps in a straight line, turn on one foot, and return in the same manner. Officers assess balance, coordination, and the ability to follow instructions.
2. One-Leg Stand Test – The driver must stand on one leg while raising the other foot approximately six inches off the ground. The officer observes for signs of impairment, such as swaying, using arms for balance, hopping, or putting the foot down.
3. Horizontal Gaze Nystagmus (HGN) Test – The officer asks the driver to follow a moving object (usually a pen or flashlight) with their eyes. If the driver’s eyes jerk involuntarily at certain angles, the officer may interpret it as a sign of intoxication.

Challenging Field Sobriety Test Results

While FSTs are widely used in DUI cases, they are not always reliable indicators of impairment. There are several ways to challenge their validity in court:

1. Test Conditions and Environmental Factors

• Poor lighting or uneven surfaces can make it difficult for a sober person to perform the tests correctly.
• Weather conditions, such as strong winds or extreme temperatures, can impact balance and concentration.
• Improper footwear (such as high heels or sandals) can cause balance issues unrelated to intoxication.

2. Officer Conduct and Test Administration

• Officers must strictly follow NHTSA guidelines when administering FSTs.
• Failure to provide clear instructions can lead to misunderstandings that affect performance.
• Subjectivity plays a role—officers may misinterpret normal movements as signs of impairment.

3. Medical Conditions and Physical Limitations

• Neurological disorders, injuries, or inner ear conditions can affect balance and coordination.
• Certain medications can cause involuntary eye movements that mimic signs of intoxication in the HGN test.
• Anxiety or nervousness during the test can also lead to mistakes.

The Importance of Video Evidence

Dashcam and bodycam footage from the traffic stop can provide crucial evidence when challenging FST results. Video recordings can:

• Show whether the officer properly instructed and administered the tests.
• Reveal environmental conditions that may have affected performance.
• Demonstrate inconsistencies in the officer’s testimony and the actual test results.

If you have been charged with a DUI in Arizona based on FST results, consulting with an experienced DUI defense attorney is essential. They can review the circumstances of your test, challenge its validity, and work to build a strong defense on your behalf.