Field Sobriety Tests

If you are pulled over by the police and suspected of driving under the influence of alcohol or drugs, officers have a variety of tests that they can administer to determine if sufficient evidence exists to arrest you for DUI. These field sobriety tests, or FSTs, are in most instances used before a breathalyzer test is performed. From law enforcement’s point of view, these tests are a way to see if someone is driving while impaired and to gather evidence that further investigation, like a breathalyzer test, should be given. Below are descriptions of each of these tests.

Standardized Field Sobriety Tests
The National Highway Traffic and Safety Administration (NHTSA) has given its endorsement to these three standardized FSTs.

Walk and Turn: In this test, the suspect is told to take nine steps along a straight line walking heel to toe while counting the steps out loud. They must then turn on one foot and then walk back along the line going in the opposite direction counting the number of steps again. Evidence of failure of this test includes: difficulty maintaining balance while walking or turning, starting to walk too soon or stopping too soon, or taking the wrong number of steps.

Horizontal Gaze Nystagmus: When all of us turn our eyes to the side, our eyes jerk involuntarily. This involuntary jerking is called horizontal gaze nystagmus. This involuntary jerking motion is much more pronounced when someone has consumed alcohol and is impaired. The officer administering the test will hold an object about a foot from the face of the suspect and move the object back and forth, all the while looking for three separate and distinct signs in the eyes: an inability to track a moving object evenly and smoothly, jerking of the eyes within forty-five degrees of center, a definite jerking motion when the eyes are turned significantly to the side.

One-leg Stand: In this test, a suspect is told to stand and count from 1001 to 1030 for thirty seconds while raising one of his feet six inches above the ground. Evidence of failure of this test includes swaying, using your arms to maintain balance, hopping, and putting your foot down.

If a suspect fails these Field Sobriety Tests, they are then given a breathalyzer test to check blood alcohol content. If the BAC is 0.08% or higher, an arrest will be made.

Non-Standardized Field Sobriety Tests
Police officers, sheriffs deputies, and highway patrol officers also have the ability to administer so-called non-standard field sobriety tests, which are tests that do not fall into the categories described above. Examples of these tests include: tilting your head back and standing with your feet close together to see if you lose your balance; counting how many fingers an officer has raised on his hands; counting numbers backwards; saying the alphabet; or the well-known image from movies of holding your arms out wide and attempting to touch your nose with your finger. These tests, though, because they are not endorsed as standard by the NHTSA, do not have as much credibility as the standard tests described above.

Reliability of FSTs
Field sobriety tests are themselves not totally reliable indicators of impairment from alcohol or drugs. Just as importantly, the way in which the tests are administered by the law enforcement officer can reduce significantly the ability of these tests to give an accurate picture of whether someone is impaired. Here are some of the factors that come into play during FSTs and can diminish their reliability:

Poor physical condition, mental difficulty, or age: Suspects who are significantly overweight, suffer from chronic pain, have reduced mobility, are senior citizens, or have some type of mental impairment that limits their ability to listen to instructions and perform a physical task are all at risk for not being able to complete field sobriety tests to the satisfaction of the investigating officer.

Poor instructions from the officer: People are nervous when facing arrest and any sort of vague or incorrect instruction from the officer can cause confusion and poor performance.

Non-alcohol or drug related factors: Some people do not perform well on FSTs because they are taking a prescription medication or have just come off a long shift at work and are mentally and physically exhausted.

Inadequate testing environment: This refers to situations when tests are given in the rain or wind or on an uneven area next to the road or even when there are bright lights and loud noises.

Clothing that is too tight or uncomfortable: If you are wearing clothes that make it difficult to move or in anyway make it difficult to comply with the officer’s instructions, that can result in inadequate FST performance.