Field Sobriety Test Defense in Illinois

Field Sobriety Tests Are Not Reliable

Field sobriety tests are designed for failure. Even completely sober people regularly fail these tests due to nerves, physical conditions, poor instructions, or environmental factors. The government's own studies show these tests are only 65-77% accurate under ideal conditions.

In real-world conditions—nervous on the side of the road, with traffic passing, possibly at night, on uneven pavement—accuracy drops even further. That's why FST evidence is regularly challenged and often excluded or discredited.

The Three Standard Tests

• Horizontal Gaze Nystagmus (HGN): The "eye test" where an officer watches for involuntary jerking. But nystagmus occurs naturally in many people and can be caused by medications, medical conditions, or fatigue.
• Walk and Turn: Nine heel-to-toe steps, turn, nine steps back. Requires balance many sober people don't have, especially under stress or in inappropriate footwear.
• One-Leg Stand: Stand on one leg for 30 seconds. Age, weight, physical conditions, and nerves all affect performance regardless of alcohol consumption.

Common Challenges to FST Evidence

• Improper Administration: Officers must give specific instructions in a specific way. Failure to follow NHTSA protocols undermines results.
• Environmental Conditions: Poor lighting, uneven surfaces, weather conditions, and traffic distractions all affect performance.
• Physical Conditions: Inner ear disorders, back problems, leg injuries, obesity, and age over 65 all provide legitimate explanations for poor performance.
• Footwear: High heels, flip-flops, or uncomfortable shoes can cause failure unrelated to impairment.
• Officer Bias: Officers may interpret borderline results as "failure" because they've already decided to arrest.
• Lack of Video Evidence: Without dashcam footage, it's the officer's word about performance—and that can be challenged.

Medical Conditions That Affect Performance

• Inner ear disorders or vertigo
• Back, hip, knee, or leg problems
• Neurological conditions
• Diabetes and blood sugar issues
• Obesity (weight affects balance)
• Age over 65
• Anxiety disorders
• Certain medications

If any of these apply to you, it's critical information for your defense. Medical records can establish legitimate reasons for poor FST performance.

What Andy Examines

With 25+ years of exclusive DUI defense experience, Andy knows exactly what to look for in FST evidence. For every case involving field sobriety tests, he examines:

• Dashcam or bodycam footage of the tests
• Officer's training and certification records
• Weather and lighting conditions at the scene
• Surface conditions where tests were administered
• Your medical history and physical limitations
• Exact instructions given by the officer

In DuPage and Will County cases, Andy often finds that officers deviate from NHTSA protocols—administering tests on sloped surfaces, giving incomplete instructions, or interpreting results with confirmation bias. These deviations can be the difference between conviction and dismissal.

Drug DUI and Field Sobriety Tests

Field sobriety tests are even less reliable for detecting drug impairment than alcohol. Standard FSTs were designed for alcohol detection and have never been validated for drug impairment. Andy is DRE/ARIDE certified—Drug Recognition Expert and Advanced Roadside Impaired Driving Enforcement trained—giving him unique insight into how law enforcement evaluates suspected drug impairment and where their procedures fall short.

Related Topics: How to Beat a DUI • Breathalyzer Defense • Getting Charges Dismissed • First DUI in Illinois • License Suspension & 90-Day Deadline • Professional License Defense • Service Areas