Field Sobriety Tests in Wisconsin: What You Need to Know

If you're pulled over on suspicion of OWI in Wisconsin, the officer will likely ask you to perform field sobriety tests (FSTs). These are physical and cognitive exercises designed to assess your balance, coordination, and ability to follow instructions — all of which can be impaired by alcohol or drugs.

But here's what most people don't know: field sobriety tests are voluntary in Wisconsin. You are not legally required to perform them.

The Three Standardized Field Sobriety Tests

The National Highway Traffic Safety Administration (NHTSA) has standardized three field sobriety tests. These are the only tests that have been scientifically validated:

1. Horizontal Gaze Nystagmus (HGN)

The officer moves a pen or flashlight horizontally in front of your eyes and looks for involuntary jerking (nystagmus). The theory is that alcohol causes more pronounced nystagmus at certain angles. The officer checks for three clues in each eye: lack of smooth pursuit, distinct nystagmus at maximum deviation, and onset of nystagmus before 45 degrees.

2. Walk-and-Turn (WAT)

You're asked to take nine heel-to-toe steps along a straight line, turn, and take nine steps back. The officer looks for eight possible clues: losing balance, starting too soon, stopping while walking, not touching heel-to-toe, stepping off the line, using arms for balance, making an improper turn, and taking the wrong number of steps.

3. One-Leg Stand (OLS)

You're asked to stand on one foot with the other foot raised about six inches off the ground, while counting aloud. The officer looks for four clues: swaying, using arms for balance, hopping, and putting the foot down.

Are Field Sobriety Tests Accurate?

According to NHTSA's own research, the standardized tests are not 100% accurate. When administered perfectly under ideal conditions:

• HGN test: 77% accurate at predicting BAC above .08
• Walk-and-turn: 68% accurate
• One-leg stand: 65% accurate
• All three combined: 80% accurate

That means even under perfect conditions, these tests falsely identify sober people as impaired 20% of the time. And in real-world conditions — poor lighting, uneven pavement, bad weather, nervousness, medical conditions — the accuracy is much lower.

Should You Refuse Field Sobriety Tests?

This is a personal decision that depends on your specific situation. Here are the considerations:

Reasons to politely decline:

• FSTs are subjective and difficult to pass even when sober
• The results give the officer evidence to use against you
• Many factors (nervousness, fatigue, medical conditions, poor footwear, uneven ground) can affect performance
• You have the legal right to refuse them

Reasons to consider participating:

• Refusing can make the officer more likely to arrest you (they may view refusal as suspicious)
• If you're confident you can perform well, passing the tests might convince the officer not to arrest you

If you choose to decline, do so politely. Say something like, "Officer, I'm respectfully declining to perform field sobriety tests. I'd like to speak with my attorney."

Important: FSTs vs. Chemical Tests

Field sobriety tests are voluntary. But if you're arrested, Wisconsin's implied consent law requires you to submit to a chemical test (breath, blood, or urine). Refusing a chemical test carries automatic license revocation penalties. These are two separate things — you can refuse FSTs but still be required to take a chemical test after arrest.

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