Police often treat field sobriety tests (FSTs) as objective proof of intoxication. However, these roadside exercises are highly subjective and prone to error. An arrest based on a “failed” test is not the end of your DUI case.
You have a right to challenge these deficient results. Understanding the weaknesses in all three FSTs is essential to defending your rights.
Horizontal gaze nystagmus
The HGN test requires an officer to track your eyes as you follow a moving object, like a pen. The officer looks for involuntary jerking in your eyes, which they claim alcohol causes. Common flaws with the test include:
- Pre-existing medical conditions, such as inner-ear problems, can cause involuntary eye movements.
- Poor lighting, rain, or the officer moving the object too quickly can make the test inaccurate.
The HGN test can suggest impairment even in a completely sober person. The results are generally inadmissible at a Pennsylvania DUI trial as substantive evidence of intoxication because the scientific foundation for the test has not been adequately established under Pennsylvania law. However, the prosecution often uses these results in a suppression hearing to help establish probable cause for the arrest.
Walk-and-turn
In the walk-and-turn test, the officer asks you to walk a straight line, taking nine steps from heel to toe, then turn around and walk back. The test is already difficult for many people.
- Uneven pavement, sloped roads or wind can affect your balance during the test.
- Your footwear, a nervous fear of falling, or even your age can impact performance.
- The officer’s failure to give clear, standardized instructions creates an inherent flaw.
These outside factors or an officer’s imprecise instructions can cause you to “fail” a test even when you are sober.
One-leg stand
For the one-leg stand test, the officer directs you to count out loud for 30 seconds while balancing on one foot. This test also suffers from significant flaws and from the officer’s subjective scoring.
- Weight, injury, or inner ear issues can naturally impair your balance.
- Cold weather or a genuine fear of falling can cause you to sway or put your foot down.
These physical and environmental factors, not intoxication, often cause issues with this test. “Failed” tests frequently result from an officer’s misinterpretation.
Refusing FSTs vs. chemical tests
If an officer stops you on suspicion of DUI, it is vital to understand the difference between roadside FSTs and chemical tests. Pennsylvania’s “implied consent” law applies only to post-arrest chemical tests, such as a breath or blood test.
While you can legally and politely refuse to perform roadside FSTs without facing an automatic driver’s license suspension, a refusal to perform these tests is generally admissible in court for the purpose of establishing probable cause for the arrest and/or demonstrating a defendant’s consciousness of guilt. This vulnerability underscores the need for securing skilled legal representation to protect your rights and challenge these tests in court.