How Reliable Are Field Sobriety Tests in Michigan? (What Drivers Need to Know in 2026)

If you were arrested for OWI in Michigan, chances are your traffic stop included field sobriety tests — the walk-and-turn, the one-leg stand, and the eye test (HGN). Officers rely on these tests heavily, often using them as the primary basis for making an arrest.

But here’s the truth:

Field sobriety tests are far from perfect.

In many cases, they are performed incorrectly, interpreted incorrectly, or impacted by factors that have nothing to do with alcohol.

As a former prosecutor who now defends OWI cases across Michigan, I can tell you that field sobriety tests are one of the most frequently challenged — and misunderstood — parts of a DUI case.

Let’s break it all down clearly.

⭐ What Are Field Sobriety Tests (FSTs)?Michigan officers generally use three standardized tests approved by the National Highway Traffic Safety Administration (NHTSA):

1. Horizontal Gaze Nystagmus (HGN) — the eye test
2. Walk-and-Turn — heel-to-toe walking
3. One-Leg Stand — balancing on one leg

These tests were created to help officers estimate impairment, but they are only reliable when performed and interpreted correctly — and that rarely happens.

⭐ 1. HGN (Horizontal Gaze Nystagmus): The Most Misunderstood Test

HGN looks for an involuntary jerking of the eyes.

Problems with HGN in Michigan:

• Most officers are not trained well enough to perform it properly
• Many don’t check for medical or eye conditions
• The test must be done at correct angles and speeds
• Lighting, wind, traffic, and flashing lights interfere
• The officer must use a specific stimulus distance
• The subject must keep their head still — often impossible roadside

What most people don’t know:

HGN is NOT admissible as scientific evidence of BAC in Michigan courts.

Judges know the test is flawed. Therefore:

• HGN alone cannot justify an arrest
• HGN cannot prove you were intoxicated
• Any mistakes in HGN undermine the officer’s credibility

If the officer relied heavily on HGN to justify arrest, that’s a red flag — and it can be used to challenge probable cause.

⭐ 2. Walk-and-Turn: The Test Almost No One Performs “Perfectly”

This test requires you to:

• walk heel-to-toe
• maintain balance
• keep arms at your sides
• take exactly nine steps
• pivot in a precise manner
• walk back nine steps

Here’s the problem:

Most sober people struggle with this test.

Even NHTSA admits the walk-and-turn is only about 66% accurate — when done perfectly and under ideal conditions.
Michigan’s roadside conditions are rarely perfect:

• snow, ice, or rain
• uneven pavement
  
• poor lighting
• passing traffic
• nerves
• fatigue
• footwear issues
• pre-existing injuries

Even mild anxiety can affect performance — let alone the stress of a flashing-lights traffic stop.

Officer errors that break this test:

• giving incorrect instructions
• starting the timer while still explaining
• using an uneven surface
• not demonstrating properly
• moving too quickly through instructions
• miscounting clues

If the test wasn’t done exactly as NHTSA requires, your attorney can challenge its validity.

⭐ 3. One-Leg Stand: A Balance Test, Not an Alcohol Test

This test requires you to:

• lift one foot six inches
• keep your leg straight
• look at your toe
• count out loud
• stay perfectly balanced

This test is only about 65% accurate even under perfect conditions.

Now think about real roadside conditions:

• anxiety
• gravel
• sloped pavement
• headlights
• winter winds
• fatigue after a long day
• age or physical limitations

A client with:

• bad knees
• back pain
• weight issues
• ankle injuries
• vertigo
• post-surgery limitations

…can easily “fail” this test while completely sober.

⭐ Are Field Sobriety Tests Required in Michigan? No.

You can legally refuse field sobriety tests in Michigan.
Refusing:

• is NOT a crime
• does NOT add license points
• does NOT trigger automatic suspension

Officers might still arrest you, but you won’t be penalized for declining the tests.
Most people don’t know this — which is why officers rarely mention that FSTs are voluntary.

⭐ Why Officers Get Field Tests Wrong So Often

Most officers in Michigan:

• do not perform NHTSA training regularly
• rely on muscle memory instead of protocol
• rush through steps
• skip medical rule-outs
• ignore environmental factors
• add clues that aren’t part of the standardized system

Any deviation from NHTSA standards makes the test scientifically unreliable.
That’s why the police report might say “failed,” but the bodycam tells a very different story.

⭐ Why Field Sobriety Tests Are Still Used Despite Being Unreliable

Because the law still allows officers to:

• observe
• interpret behavior
• form probable cause

FSTs help officers justify an arrest.
But that doesn’t mean they prove intoxication.

In court, the question isn’t:
“Did the officer think you were impaired?”
It’s:
“Is the evidence reliable enough to convict?”
These are two very different standards.

⭐ How Field Sobriety Test Problems Lead to Dismissals and Reductions

When field tests are flawed, your defense attorney can challenge:

• probable cause for arrest
• the legality of the stop
• the reliability of observations
• the validity of the breath test
• officer credibility
• the admissibility of evidence

Weak FSTs often result in:

• dismissals
• major reductions (OWI → Impaired)
• suppression of key evidence
• better sentencing outcomes

Your attorney will use the bodycam, dashcam, and NHTSA manual to show exactly where the test broke down.

⭐ Final Thoughts: Field Sobriety Tests Are Not the Final Word

​Field sobriety tests are tools — not proof.
They can be helpful, but only when performed correctly. In reality, most Michigan officers do not execute them precisely, and most drivers are tested under conditions that would challenge anyone.
That’s why these tests are one of the first things I examine when building a defense.