Field Sobriety Tests (FST's)

Field Sobriety Tests are tests that an officer gives to a person being evaluated for a DUI. Generally these tests are done by the side of the road, and the information an officer gathers during these tests provide the bulk of the evidence used against a person arrested for a DUI.

Field Sobriety Tests (sometimes referred to as “FST’s”) fall into two categories – Standardized Field Sobriety Tests (sometimes referred to as SFST’s) and non-standardized tests.

Standardized Field Sobriety Tests

Years ago there were scientific studies conducted to determine the likelihood that a person is impaired based on how well they performed three different field sobriety tests administered in a consistent, standardized way. These three tests, the Horizontal Gaze Nystagmus Test, the Walk-and-Turn Test and the One-Leg Stand Test are now called Standardized Field Sobriety Tests. In theory, as long as an officer administers the test exactly the same way and looks for exactly the same clues, the test results are given extra weight, based on the statistics from those original studies.

Horizontal Gaze Nystagmus (referred to as “HGN”)

The HGN test is probably the most scientifically accurate of the three standardized field sobriety tests, as long as the officer administers the test correctly. Nystagmus is an involuntary jerking of a person’s eye. There are many types of nystagmus, and some people even have it naturally, but the type of nystagmus the officers are looking for, Horizontal Gaze Nystagmus, generally appears in a person after a person consumes certain intoxicants, including alcohol. Nystagmus is an involuntary muscle reaction, so a person can’t control it, and even if it is present, the person’s brain essentially averages out the movement, so you don’t know if it is present or not.

In this test, an officer has a person stand, feet together, hands down at their sides, and asks the person to follow a stimulus, usually a pen or fingertip, with their eyes. As the stimulus is moved horizontally in front of the person’s face the officer is looking to see if a person can follow directions (only move their eyes and not their head and keep their hands at their sides) and whether the person has any sway as he or she stands in front of the officer, but that isn’t the core of the test. Instead, the officer is watching a person’s eyes as their eyes move – there are six total ‘clues’ an officer looks for, three in each eye. If the officer observes four or more clues, the officer will conclude that the person failed this test.

The Walk-And-Turn Test

I think from a citizen’s perspective we would all like these field sobriety tests to be a fair and accurate way to see if someone has had too much to drink, but in reality, I often see people with very low breath test results fail a field sobriety test because, in their nervousness and fear, they didn’t fully understand the directions and how they were actually being graded. The Walk-and-Turn test is a good example of this.

This is the test that most folks think of as the ‘walk the line’ test, and everyone thinks that the main purpose of this test is to see if a person can maintain balance while walking on a straight line. In reality, keeping your balance is just one of eight ‘clues’ a person is being graded on in this test, and you can fail this test before you even start walking!

Here are the verbal instructions that should accompany a three-step example given by an officer, according to the officer’s training manual:

“Place your left foot on the line. Place your right foot on the line ahead of the left foot, with the heel of your right foot against the toe of your left foot. Place your arms down at your sides. Keep this position until I tell you to begin. Do you understand the instructions so far? When I tell you to start, take nine heel-to-toe steps, turn, and take nine heel-to-toe steps back. When you turn, keep the front foot on the line, and turn by taking a series of small steps with the other foot. While you are walking, keep your arms at your sides, watch your feet at all times, and court your steps out loud. Once you start walking, don’t stop until you have completed the test. Do you understand the instructions?”

A person taking this test is allowed to make one mistake (what the officer views as one ‘clue’). If he or she makes a second mistake, the officer will view this as a failure of the test. Here are the eight clues an officer looks for:

  1. the person does not maintain heel-to-toe contact during the entire test instructions;
  2. the person starts the test before being told “begin;”
  3. the person pauses for several seconds at any point once the test begins;
  4. the person misses heel-to-toe by more than ½ an inch during any step;
  5. the person steps off the line by more than 3 inches during any step;
  6. the person lifts one or both arms more than six inches from their side;
  7. the person turns incorrectly – removing the front foot from the line while turning is a clue; so is a spin or pivot turn;
  8. the person takes more or fewer than nine steps.

In my personal opinion, this test is far from precise. A person who fails this test may or may not be under the influence of intoxicants, and I think many people who would pass this test in their living room don’t pass it on the street because their nerves and fear, together with not fully understanding how they are being graded, skews their results.

The One-Leg Stand Test

The One-Leg Stand test is the last of the three standardized field sobriety tests. In this test, a person is told to begin by standing with their feet together, arms down at their sides and then the officer tells them to:

“Raise one leg, either leg, approximately six inches off the ground, foot pointed out. You must keep both legs straight, arms at your side. While holding that position, count out loud in the following manner: “one thousand and one, one thousand and two, one thousand and three, until told to stop.” Keep your arms at your sides at all times and keep watching the raised foot.”

A person taking this test is allowed to make one mistake on this test too (what the officer views as one ‘clue’). A second mistake means that the officer will view this as a failure of the test. Here are the four clues an officer looks for:

  1. the person sways while balancing on one leg;
  2. the person moves arms more than six inches from their sides to keep balance;
  3. the person hops while balancing;
  4. the person puts his or her foot down before being told to.

This test is supposed to last thirty seconds, although the person taking the test only knows to keep going until the officer tells them to stop. In the officer’s training manual it tells the officer to be very still when administering this test “so as to not interfere.” If an officer moving his or her body can interfere with the test, the cars and trucks that pass within ten feet of a person taking this test on a freeway would seem to make this test much more difficult than designed.

Non-Standardized Field Sobriety Tests

I guess I’ve been doing this long enough that I can talk about ‘the way things used to be’ (I tried my first DUI case in 1997 as a prosecutor while I was still in law school). The decrease in officers use of non-standardized field sobriety tests has been a big change in the last 18 years. Back then, officers often used whatever tests they personally liked, without any real concern about police agency standardization or of scientific validation. Over the years most of these tests have fallen out of favor, but a few are still used from time to time, often when cases involve a very senior officer who is remembering his or her distant training, or when a person cannot perform the standardized field sobriety tests due to a particular situation or disability.

Number Count Test

The most common number count test I see is to have a person count backwards, beginning and ending at a random number. For example, the officer may ask a person to count backwards from 91 to 77. I’ve also seen officers ask a person to count backwards by twos or threes, again beginning and ending at random places.

Finger Dexterity Test

For this test an officer asks a person to touch the tip of their thumb to the tip of each finger on the same hand while counting forwards and backwards “one, two, three, four, four, three, two, one” as each finger is touched. Sometimes an officer will request a person to do this one hand at a time, while other officers may require that a person do this on both hands simultaneously.

Touch Your Nose Test

For this test, an officer asks a person to lean back, arms spread wide, and when asked, touch the index finger of the side the officer calls (right or left) to the tip of the nose and then bring the hand back, all while keeping the arms extended. While this may be one of the tests most shown on U-Tube, in my experience Oregon officers don’t use this test much for alcohol-based DUI investigations anymore. It is used when an officer is investigating a drug-based DUI though, and this test is part of the standard Drug Recognition Evaluation (sometimes referred to as a “DRE”) that officers use to determine impairment based on a prescription drug or an unlawful controlled substance.

Alphabet Test

There are two ways I’ve seen officers use this test. The first is to recite a portion of the alphabet forward, and this is a legitimate use of this test, in my humble opinion. The second is, again in my opinion, deceptive and unfair, and that is to ask a person to recite the alphabet backwards.

During the legitimate use of this test, an officer will ask a person to recite the alphabet forward, beginning and stopping at random letters. For example, a person may be asked to recite the alphabet from “j” to “p” without singing the letters in the ABC saying most of us learned in grade school.

The deceptive use of this test is in asking a person to say the alphabet backwards. Let me share something – nobody can say the alphabet backwards! The officer asking this question doesn’t expect the person to perform this test at all. The only reason an officer asks a person to perform this test is to get the person to say “I couldn’t do that sober.” That statement is then used to imply that the person wasn’t sober at the time he or she made the statement.

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