Field sobriety tests are commonly used by police officers to check whether a driver may be impaired by alcohol or drugs during a traffic stop. These tests help an officer observe balance, coordination, focus, and ability to follow instructions. Although many people think these exercises are simple, they require attention to detail, clear movements, and calm behavior. Understanding field sobriety test instructions can help individuals know what to expect in roadside situations and better understand how officers evaluate impairment. This topic explains common field sobriety test steps, the purpose behind them, and important considerations for drivers. It does not offer legal advice but instead aims to provide clear information in an easy-to-read format.
What Is a Field Sobriety Test?
A field sobriety test, often called an FST, is a physical and cognitive assessment conducted roadside. These tests are used by law enforcement to evaluate whether a driver shows signs of intoxication. Field sobriety tests are standardized, meaning they follow specific instructions and scoring methods to help keep results consistent. While performance on these tests can contribute to decisions made by officers, they are not the only factor considered during a traffic stop.
Standardized Field Sobriety Tests
There are three main standardized field sobriety tests widely recognized and used by police officers. Each test checks different functions, such as eye movement, balance, listening ability, and mental focus. Official instructions must be given clearly, and drivers are expected to follow them precisely.
The Three Standard Field Sobriety Tests
- Horizontal Gaze Nystagmus (eye movement test)
- Walk-and-Turn test
- One-Leg Stand test
Each of these tests serves a unique purpose and is performed in a specific order. Officers usually explain the instructions before beginning and may demonstrate the steps so the driver understands what is expected.
Horizontal Gaze Nystagmus Test
The first common field sobriety test involves examining the eyes. Horizontal Gaze Nystagmus, or HGN, refers to involuntary jerking of the eyes that becomes more visible when someone is impaired by alcohol. The officer uses an object, usually a pen or small light, and asks the individual to follow it with their eyes without turning their head.
Basic Instructions for HGN
- Stand with feet together and hands at sides
- Keep head still and follow the officer’s object with only the eyes
- Focus on the object as it moves side to side
During this test, the officer watches the eyes for smoothness of movement, ability to track the object, and signs of jerking at certain angles. This test requires no walking or balancing, but focusing steadily is essential.
Walk-and-Turn Test
The walk-and-turn test measures balance, coordination, and ability to follow multiple instructions at once. Many drivers find this test challenging because it requires attention to both movement and direction. Officers typically conduct this test on a flat, dry surface.
Walk-and-Turn Instructions
- Stand heel-to-toe with arms at sides while listening to instructions
- Do not begin walking until told to start
- Take nine heel-to-toe steps in a straight line
- Keep arms at sides and watch feet while walking
- Turn carefully using small steps
- Return with nine heel-to-toe steps
During this test, the officer watches for signs such as stepping off the line, losing balance, using arms for balance, stopping before completing steps, or turning incorrectly. Clear following of directions is important for completing the test successfully.
One-Leg Stand Test
The one-leg stand is a balance test that checks stability and concentration. It requires standing on one foot while counting aloud. This test helps officers watch for swaying, hopping, or difficulty maintaining balance.
One-Leg Stand Instructions
- Stand with feet together and arms at sides
- Lift one foot about six inches off the ground
- Keep the leg straight and foot pointed forward
- Look at the raised foot
- Count aloud until instructed to stop
The officer observes whether the person sways, uses arms for balance, puts the foot down, or hops. Maintaining focus and control makes a difference in how performance appears.
Non-Standard Field Sobriety Tests
Although the three standardized tests are most commonly used, officers sometimes use additional exercises to observe behavior. These may include reciting parts of the alphabet, touching fingertips to the nose, or counting backward. These tests vary and are not always uniform across regions.
Examples of Non-Standard Exercises
- Finger-to-nose test
- Counting steps or numbers backward
- Alphabet recitation without singing
These tests still focus on coordination and mental clarity but may not have the same structured scoring as standardized tests.
Importance of Following Instructions
One key goal of field sobriety test instructions is to see whether a driver can follow directions accurately. Listening closely and carrying out each step properly is part of the evaluation. Even small mistakes, such as starting too early or not keeping arms down, may be noted by the officer.
This does not always mean someone is impaired, as nerves, fatigue, or medical conditions can affect performance. Still, officers use both observation and conversation to assess the situation.
Common Challenges During Field Sobriety Tests
Many people feel nervous when asked to perform these tests, even if they have not consumed alcohol. Stress, uneven surfaces, physical limitations, poor lighting, and weather conditions can impact performance. Officers are trained to consider these factors, but they still rely heavily on behavior and response during testing.
Factors That Can Affect Performance
- Anxiety or nervousness
- Medical or physical limitations
- Footwear such as heels or boots
- Uneven or slippery ground
- Poor hearing or misunderstanding instructions
Why Officers Use Field Sobriety Tests
The purpose of a field sobriety test is to help ensure safe roads. By checking coordination, focus, and reaction, officers gain information that supports decisions about further testing, such as breathalyzer checks. These road tests aim to prevent accidents and protect both drivers and the public.
When people understand field sobriety test instructions, they are better prepared if ever asked to participate. Clear communication between drivers and officers helps keep traffic stops respectful and safe.
Field sobriety tests play a major role in roadside safety checks and help officers observe signs of impairment. While many people imagine them as simple exercises, they involve balance, concentration, and careful listening. Knowing common test instructions from the eye movement check to the walk-and-turn and one-leg stand can help drivers understand what officers look for and why these tests exist. The aim is not only enforcement but also prevention and public safety. Staying informed, calm, and aware of the process supports a smoother experience for everyone on the road.