FIELD SOBRIETY TEST (FST)

WHAT IS A FIELD SOBRIETY TEST (FST) FOR DUI?

Field Sobriety Test (FST) are a series of tests law enforcement use to determine if you are under the influence of alcohol or drugs (DUI)

Usually, police officers will look for blood shot eyes or watery eyes, slurred speech, smell of alcoholic beverages (note: the smell is from the beverage, not the alcohol, as ethanol really has no odor at all), smell of drugs and overall appearance

If a police officer asks you to exit your vehicle, he or she is already suspicious of a DUI and will immediately administer a set of FSTs including perhaps a Preliminary Alcohol Screening test to determine whether they have probable cause to arrest you

WHAT ARE THE TYPES OF DUI FIELD SOBRIETY TESTS?

There are 6 common types of FSTs used in the country, but only 3 have been approved by the NHTSA (National Highway Traffic Safety Administration). These tests are the Horizontal Gaze Nystagmus (HGN), One-Leg Stand (OLS), and Walk-and-Turn (WAT). Also, these tests are deemed standardized, having guidelines on its administration or scoring, but the other do not

Horizontal Gaze Nystagmus (HGN)

This test is considered the most accurate of all the FSTs. It tests the involuntary jerking of your eyes as it moves horizontally measuring any lack of smooth pursuit at maximum deviation and onset of nytagmus prior to 45 degrees. Nystagmus is present in all people, but it is not visible to the naked eye. However, alcohol or drugs enhance nystagmus and thus it is visible without a special device. Basically, the theory is that if you have jerking of the eyes or no smooth movement as it moves horizontally, you are considered to have consumed alcohol or drugs

Accuracy: HGN is 77% reliable in identifying those with BACs of .10% or more IF AND ONLY IF THE TEST PROCEDURE IS FOLLOWED EXACTLY

HGN combined with WAT is claimed to be 80% reliable in identifying those with BACs of .10% or more IF AND ONLY IF THE TEST PROCEDURE IS FOLLOWED EXACTLY

Walk-and-Turn (WAT)

This test is a 2 part test. Part 1, the officer will require you to stand heel-to-toe and while he gives you instructions and demonstrates the test. Part 2, the officer will then require you to take 9 step forward, heel-to-toe touching on a straight line, turn on the last step and walk 9 steps back heel-to-toe touching. A natural line must be present, or the officer must draw one on dirt or with chalk on the street

Accuracy: WAT is 68% reliable in identifying those with BACs of .10% or more IF AND ONLY IF THE TEST PROCEDURE IS FOLLOWED EXACTLY

WAT combined with HGN is claimed to be 80% reliable in identifying those with BACs of .10% or more IF AND ONLY IF THE TEST PROCEDURE IS FOLLOWED EXACTLY

One-Leg Stand (OLS)

The officer will require you to stand with your arms to your side and raise and hold one leg at least 6 inches off the ground for 30 seconds. You must count the seconds out loud. The 30 second time frame is important because according to NHTSA, a person with a BAC of .10% can maintain balance for up to 25 seconds but rarely for 30 seconds

Accuracy: OLS is 65% reliable in identifying those with BACs of .10% or more IF AND ONLY IF THE TEST PROCEDURE IS FOLLOWED EXACTLY

Romberg

The officer will instruct you to stand with your feet together, title your head back slightly and slowly, then close your eyes. Then, the officer will require you to estimate when 30 seconds has passed in your head. When you feel 30 seconds has passed you are instructed to said "stop" and bring your head forward and open your eyes

Finger to Nose

The officer will instruct you to place your feet together, stand straight, and close your eyes. Then, the officer will require you to bring you index finger and touch the tip of your nose. The officer is looking for lose of balance, tremors, tension or missing your target

Finger Tap Counting

The officer will instruct you to hold out one hand, with your palms up, and touch the tip of each finger to the tip of your thumb. Then, the officer will instruct you to count out loud after each tap for 3 consecutive sets

WHAT IS THE VALIDITY OF THE FSTs BASED ON THEIR RELIABILITY PERCENTAGES?

For the FSTs approved by NHTSA, the highest reliability percentage that identifies those with BACs of .10% or more is 80% (HGN with WAT). A score of 80% is usually a "B-" grade in school, right? This means that 20% of the time, it is not reliable! And, its only 80% reliable IF AND ONLY IF THE TEST PROCEDURE WAS FOLLOWED EXACTLY by the police officer

WHAT IF I REFUSE TO TAKE THE FSTs?

If you do, it is recommended that you "politely" let the officer know that you wish to refuse any FSTs tests

Again, if you refuse them you will most likely be arrested for DUI and will be hauled off to the local police station, hospital, or detainment center to obtain your Blood Alcohol Content (BAC). If you refuse the BAC test, then you may be cited for Refusal Enhancement