Horizontal gaze nystagmus (HGN) is typically the first field sobriety test administered by an officer during a DWI investigation. HGN is the involuntary jerking of the eyes as they gaze toward the side. HGN is the most reliable field sobriety test according to the NHTSA manuals. A persons involuntary jerking of the eyes is more noticeable when they have an increased blood alcohol concentration. However, not all causes of HGN are related to the consumption of alcohol.

Head injuries and certain disorders such as inner ear disease, brain damage, or brain tumors can result in the presence of HGN.

Other conditions that can cause HGN include:

  • Influenza
  • Vertigo
  • Epilepsy
  • Motion Sickness
  • Excess Caffeine
  • Excess Nicotine
  • Aspirin
  • Certain Diets

NHTSA also lists environmental factors that can influence the presence of HGN:

  • Wind and Dust
  • Visual Distractions


The walk and turn (WAT) field sobriety test is considered a divided attention test. The first part of this field sobriety test will consist of a set of instructions and demonstrations. The officer is testing your ability to listen to instructions at this phase. They will ask you to place your right foot in front of your left foot on a line. Next you will be asked to place your arms down at your sides and to maintain this position until the instruction phase is over.

All of that is the first part of the field sobriety test!

The second part of the WAT is the physical part. You will be instructed to take nine heel-to-toe steps in both directions, while keeping your arms at your side, counting your steps out loud, and perform a very specific turn. Once the WAT begins DO NOT STOP.

Exhibiting two or more of the following clues the officer is looking for can indicate intoxication:

  • Keeping Balance While Listening to Instructions
  • Starting Too Soon
  • Stopping While Walking
  • Not Touching Heel-To-Toe
  • Stepping off the Line
  • Using Arms for Balance
  • Improper Turn
  • Incorrect Number of Steps

Factors that could influence the results of the OLS include:

  • Individuals over 65 years old
  • People with back, leg, or inner ear problems


field sobriety tests / standardized field sobriety tests / dwi / dwi lawyer / sfts

The last sobriety test officers typically administer is called the One Leg Stand (OLS). Similarly to the WAT, the OLS is also a divided attention test. When asking you to perform the OLS, an officer will ask you to stand with your feet together with you arms down to the side. You will be instructed to not perform the test until told, followed by a question regarding your understanding of the instructions. Next, you will be asked to raise either leg with your foot six inches off the ground. Following that you will be instructed to keep both legs straight and your arms at your side. You will then be asked to count out loud until told to stop. The test should last only 30 seconds.

Clues the officer is looking for include:

  • Swaying
  • Using Arms for Balance
  • Hopping
  • Putting Foot Down

Factors that could influence the results of the OLS include:

  • Individuals over 65 years old
  • People overweight by more than 50 pounds
  • People with back, leg, or inner ear problems

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