Why Michigan Field Sobriety Tests Are Not Scientifically Reliable

There is a massive amount of research showing FSTs are limited to make an arrest for a DUI in Michigan, and are inconsistent, and often misused. 

​1. NHTSA Itself Admits Limited Accuracy

The National Highway Traffic Safety Administration — the agency promoting these tests — admits the following in its own validation studies:

• HGN: ~77% accurate
• Walk-and-Turn: ~66% accurate
• One-Leg Stand: ~65% accurate

And that’s under lab conditions, with:

• perfect instruction
• perfect surfaces
• sober volunteers
• zero stress
• zero flashing lights
• zero freezing temperatures
• no medical conditions

Roadside reality is nothing like the lab.

NHTSA’s own studies show:

• 25–35% false positives
• even more for people with medical, age, weight, anxiety, or balance issues
• non-standard clues invalidate the test entirely

That’s the government admitting their tests are flawed, which is important for a Michigan DUI arrest involving field sobriety tests. 

🔹 2. The Southern California Research Institute Studies (Burns & Moskowitz)These were the original studies NHTSA adopted. Their weaknesses:

• tiny sample sizes
• mostly young, healthy participants
• no true scientific control
• biased scoring
• high rates of false arrest cues
• almost no testing on older or heavier subjects

Modern forensic scientists criticize these studies heavily.

🔹 3. Medical & neurological research

Peer-reviewed studies show:

• nystagmus (HGN) occurs naturally from fatigue, stress, medication, caffeine, flashing lights, anxiety, neurological conditions
• heel-to-toe walking is affected by age, footwear, weight, back pain, knee pain, snow/ice, uneven roads
• balancing tests are affected by inner ear issues, vertigo, dehydration, anxiety, and even wearing boots

In short:

FSTs confuse normal physical limitations for intoxication for a DUI case in Michigan. 

🔹 4. The American Optometric Association: HGN Is Not Proof of Intoxication

They state that:

• over 40 medical conditions cause nystagmus
• dozens of medications create eye movement irregularities
• roadside conditions produce false positives

This destroys the claim that HGN equals intoxication in a Michigan drunk driving case. 

🔹 5. The Psychology: Stress Makes Everyone Perform Worse

Research in physiology and behavioral science shows:

• adrenaline spikes
• divided attention worsens
• balance drops
• heart rate increases
• motor skills decline

Meaning:

A perfectly sober person can “fail” a Michigan field sobriety test just by being terrified during a traffic stop.