skip to Main Content

OVI Field Sobriety Tests from the NHTSA Manual


The National Highway Traffic Safety Administration (NHTSA), puts out a Federal Vehicle Safety Standards Manual for law enforcement to use in OVI investigations. This is manual contains specific instructions that police officers must follow in order to establish probable cause to arrest someone for operating a vehicle under the influence and reasonable suspicion to request a chemical test.

If the instructions are not followed as instructed in the manual, the test results are not reliable. When scrutinized by a trained eye, many of these field sobriety tests administered by police officers are not done properly and the results are unreliable. This is in part because after graduating from the police academy, many police officers do not maintain good training on how to administer the tests per the NHTSA manual.

From the NHTSA Manual, three field sobriety tests are recommended to be used by the investigating officer. These tests are physically difficult for anyone and, arguably, are designed to fail.

The three tests are:
  • The Horizontal Gaze Nystagmus test (HGN)
  • The Walk and Turn test (WAT)
  • The One Leg Stand test (OLS)
The Horizontal Gaze Nystagmus test (HGN)

In the HGN, an officer will tell you to put your feet together and follow the officer’s finger or stimulus (usually a pen) with your eyes without moving your head. During this test, the officer will be watching your eyes to see if they move smoothly or jerk noticeably. Improper instructions, the interference of oncoming headlights, or the wearing of contacts can render such a test invalid in establishing probable cause for an arrest.

The Walk and Turn test (WAT)

For the WAT test, an officer will ask you to take nine steps heal-to-toe in a straight line, turn around and walk back the same way while staying on the line and keeping your arms at your side. This can become more difficult when trying to listen to subsequent directions given by the officer while the test is being performed. During the test, an officer will be looking for the following indicators of impairment:

  1. whether you are unable to maintain your balance while listening to the officer’s instructions;
  2. whether you begin walking before the officer has completed the instructions;
  3. whether you stop while walking in order to regain your balance;
  4. whether you actually touch your feet heel-to-toe;
  5. whether you use your arms to maintain your balance (more than 6 inches from your body);
  6. whether you lose your balance while turning; and
  7. whether you take an incorrect number of steps.

The presence of two or more of these indicators can meet the probable cause requirement for an officer to make an arrest. This test can be considered invalid if improper instructions were given. In addition, this test has been criticized because of the officer’s subjective perception of each indicator. This means that if the officer wants you to fail, he or she could potentially look for reasons to fail you when you would otherwise pass. A videotape taken by the police vehicle of the test can benefit the defendant if this occurs.

The One Leg Stand test (OLS)

For this test, you would be asked to stand with both feet together and hands at your side. You would then have to raise one foot about six inches above the ground and count to 30. The Officer will then be looking for one of the following indicators of intoxication:

  • Swaying
    • Swaying is when you move your hips from side to side in order to keep your balance.
  • Using the arms to keep balance
    • Raising your arms six inches above your side in order to keep your balance is interpreted to mean you are having significant trouble keeping your balance.
  • Hopping on the anchor foot in order to maintain balance
    • Any raising of the anchor foot off the ground is considered an indicator of impairment.
  • Resting the raised foot on the ground three or more times during the required thirty seconds of the test
    • Doing this is considered an inability to complete the test and is an indicator of impairment.
Back To Top