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What Are Field Sobriety Tests?

Field Sobriety Tests (FSTs) are the roadside examinations administered by the police officer in investigating whether you were operating your vehicle under the influence of alcohol. Field sobriety tests are specific tests and were developed and sponsored by the National Highway Traffic Safety Administration (NHTSA). The standardized field sobriety tests, if given in a prescribed manner, under a standardized setting, supposedly demonstrate validated indicators or cues of a person's impairment. When the tests are administered in the manner detailed by the NHTSA and an officer observes these cues, it allows him to establish probable cause to believe an operator is impaired and arrest that person for OUI. The three primary standardized field sobriety tests are:
  1. Horizontal Gaze Nystagmus.
    In the performance of this test, an officer asks a suspect to following a pen or small flashlight, tracking left to right with his eyes. A person's eyeball jerking (nystagmus) is magnified by the amount of impairment due to alcohol. This test is regularly deemed inadmissible in Massachusetts. Despite its non­evidentiary use, police officers conducting tests roadside regularly utilize this test in the formation of probable cause to place a suspect under arrest for OUI.
  2. Nine­Step Walk and Turn.
    The nine­step walk and turn test is a two­part examination. The first part is the instruction phase. The officer is conducting observations of the operator during the course of the instruction phase of this test. During this time, the officer is verbally instructing and physically demonstrating how he wishes this test to be performed. The operator is advised to stand still, feet together, hands at his side during the performance of the instruction phase. He is also instructed not to start the test until all of the instruction and demonstration is complete. The officer will typically make and record observations of an operator during this phase. The second phase is the performance of the test. What is required in the physical performance of the test is that the subject walk on a straight line, one foot in front of the other, touching heel to toe, keeping his arms to his side, counting the steps out loud. The subject is required to take nine steps out, articulate a turn at the end and take nine steps back in the same manner. During the performance of this test, the officer is watching for eight cues of impairment:
    1. Loses balance during instruction
    2. Starts test before instructions are finished
    3. Stops during performance of test to steady self
    4. Fails to touch heel to toe
    5. Steps off of line
    6. Uses arms for balance
    7. Loses balance or turns improperly
    8. Takes the wrong number of steps

    If a suspect demonstrates two of these eight cues at any time during the performance of this test, the subject is deemed to have failed this test. This test demonstrates a 68 percent probability that the subject is under the influence of alcohol and has a BAC of .10 or more.

  3. One Leg Stand Test.
    Like the nine­step walk and turn test, the one leg stand test also is a two­stage test, instruction and performance. During the instruction stage, the suspect is required to stand with his feet together and his arms at his side. The officer will verbally instruct and demonstrate the performance of this test for the subject. The performance stage of this test requires that the subject stands with one foot of their choice approximately 6 inches off the ground, straight out in front of them and counts out loud by thousands for 30 seconds. The suspect is advised not to hop on the one foot or to use his arms for balance. During this test, the officer is trained to observe for four cues of impairment:
    1. Swaying while balancing
    2. Using arms for balance
    3. Hopping to maintain balance
    4. Putting foot down before completion of test

    If an officer observes two or more of the above cues, this test demonstrates a 65 percent probability that the subject has a blood alcohol content of .10 or more.

  4. CONDITIONS
    There are certain conditions, under which the tests should be administered, as required by the NHTSA. The tests are to be administered on a hard, dry, clean, non­slippery surface in a well­lighted area. Tests that are administered in less than standardized conditions diminish the results which an officer might obtain. The tests that are mentioned above are the only tests that are scientifically validated for use by an officer in detecting intoxication in an operator. Oftentimes you will see or hear about tests such as touching finger to nose, picking up coins, and counting backwards being utilized by officers as field sobriety tests. There is no scientific validation for these tests and they offer little reliability for the officer to accurately detect impairment. Remember, if any element of the standardized field sobriety test is altered or compromised, then the validity and reliability of the test is compromised. These compromises work in your favor.

    In Massachusetts, an operator has a right to refuse to perform field sobriety tests. By performing field sobriety tests, you are only providing evidence to the officer in forming his OUI case against you. An operator is advised to exercise their right to refuse the performance of field sobriety tests. In the typical administration of field sobriety tests, a police officer will not describe to the subject the criteria he is looking for in the performance of this test. The officer typically will not describe to the subject the various cues he is looking for. The officer typically will not describe the number of cues necessary to formulate the failure of the test by the operator. In a typical stop, the officer will ask the operator to perform several field sobriety tests. At the conclusion of those tests, the officer will inform the operator that he is placing the subject under arrest. Prior to advising the operator they are under arrest, the officer will have virtually no discussion with the operator about the performance of the tests.

    Remember, everything you say and everything you do can and will be used against you in a court of law. Be smart and protect yourself.

  5. DISCLAIMER
    This FAQ is intended as an overview of basic field sobriety tests administered by local police departments as instructed by the NHTSA. The foregoing is provided for information purposes only. For a more encompassing discussion of field sobriety testing, you should consult in person with a qualified criminal defense lawyer.

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