Field Sobriety Tests

“Field Sobriety Test” (FST) is a term used to refer to a series of tests law enforcement officers ask people to perform on the side of the road at or near where they have been stopped on suspicion of driving while impaired, due to alcohol or drug use. The belief is that one’s ability or inability to perform the field sobriety tests as instructed is an indication of sobriety or impairment.


In most jurisdictions, including Washington D.C., Virginia, and New York, field sobriety tests have, in theory, been standardized. In other words, police have been trained to administer tests and evaluate responses with an eye towards uniformity in both the testing and the results. The standard tests are:

  • Walk and Turn;
  • One Leg Stand; and
  • Horizontal Gaze Nystagmus.

These tests have been sanctioned by the National Highway Traffic Safety Administration (NHTSA). They are designed to measure a specific response, in the case of the one leg stand and the walk and turn test, and a reflex in the case of the horizontal gaze nystagmus test. It is believed if one is intoxicated, one will respond differently than if one is sober.


In the walk and turn test, participants are asked to take nine steps in a row, heel to toe. These nine heel-to-toe steps must be taken in a straight line. At the end of the nine steps, the test taker must turn on one foot 180 degrees. Then the test taker is instructed to walk back, using the same heel-to-toe method.

In this test, officers are testing to see if the person can:

  • Maintain their balance while being given instruction,
  • Wait until instructions are finished before beginning,
  • Keep balance while walking,
  • Maintain heel to toe contact,
  • Walk without using their arms to balance,
  • Maintain the straight line rather than step off the line,
  • Take the correct number of steps, and/or
  • Turn properly.

Failure to maintain the above-listed behaviors is considered evidence of impairment.


In the one leg stand test, the test taker is told to stand with one foot raised about six inches off the ground. Then they are instructed to count out loud until they are told to stop. This lasts for 30 seconds. Police are looking for the following:

  • Swaying,
  • Using arms for balance,
  • Hopping on one foot, and
  • Putting a foot down.

These are considered an indication the person is impaired.


This test is based on reflex. When a person’s gaze goes up and to the side, a person’s eyes will respond by an involuntary jerking. In theory, a person impaired by alcohol shows this response at lower angles and is less able to smoothly track a moving object. When asking a person to use their eyes to follow the officer’s pen or flashlight, while the officer moves the pen or flashlight to the side and at an angle, the officer is looking for whether:

  • The eye cannot follow the object smoothly,
  • Eye movement jerking is sustained, and
  • Eye jerking occurs prior to 45 degrees of center.

When the officer observes these things, this is considered evidence of impairment.


If the police ask someone to engage in field sobriety testing, they may have already made a decision they believe the person is impaired. Often, field sobriety tests merely give police more information to confirm their suspicions about impairment.

There are arguments on both sides of the issue about whether or not taking the tests benefits the person who has been stopped. However, these tests are not mandatory and drivers will not face automatic penalties simply for refusing to submit to these highly subjective tests.


While someone who is impaired may very well fail field sobriety tests, failing field sobriety tests is not necessarily an indication of impairment. Consider both the walk and turn test and the one leg test require a certain amount of coordination and concentration. There are both physical and cognitive reasons why one may not be able to successfully complete these tests.

Further, the HGN test relies upon an officer accurately moving their flashlight or pen at the right angle and accurately estimating when a person’s eyes begin to jerk in relation to the angle. This is subjective and could be misinterpreted. Further, there are certain physical conditions which could lead to nystagmus that are not related to impairment.


If you are facing DUI or DWI charges in DC, you need a professional on your side who understands the complexities of field sobriety testing. Contact S.L. England, PLLC today to discuss your case. Call (202) 489-0720. Let us put our experience to work for you.

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