Field Sobriety Tests

Bakersfield Field Sobriety Tests

What are Field Sobriety Tests?

Field sobriety tests are used to assess a driver's level of intoxication when a law enforcement officer suspects that the person is under the influence of alcohol or drugs. These tests enable the officer to make roadside deductions of the driver's intoxication level.

The standardized field sobriety test approved by the National Highway Traffic Safety Administration (NHTSA) is a series of three tests that are systematically administered:

  • Horizontal Gaze Nystagmus (HGN)
  • Walk-and-Turn (WAT)
  • One-Leg Stand (OLS)

Arrested for a DUI? Get started on your case by contacting the experienced attorneys at Humphrey & Thompson today!

Horizontal Gaze Nystagmus

Horizontal Gaze Nystagmus is the natural jerking movements of the eye when they move to the side. When intoxicated, the jerking of the eye is exaggerated and can occur at lesser angles.

Law enforcement officers instruct drivers to follow objects such as a pen or flashlight with only their eyes while keeping their heads still. Tracking the moving object can be more difficult for someone who is impaired with alcohol. This test successfully classifies 88% of suspects as alcohol impaired.


The Walk and Turn is a test that is presumably easy for a sober person to perform. The person being tested must listen to instructions while acting out simple movements. Paying attention to two simple tasks, in this case mental and physical exercises, is challenging for a person who is impaired.

To perform this test, the individual will take nine steps, walking heel to toe, on a straight line. After taking these steps the person must make a pivot turn on one foot and return to the starting position in the same manner. This will test their balance while walking and turning.

Some of the key indicators that the suspect is impaired are:

  • Not being able to balance
  • Starting the exercise before instructed
  • Stopping to balance or using arms to balance
  • Not walking heel to toe
  • Not remaining on the line while walking
  • Not following the instructions correctly

If two or more of these indicators are seen in their exercise, there is a 79% indication that the suspect is intoxicated above the legal limit.

One-Leg Stand

The One-Leg Stand is a test that requires the suspect to stand with one foot about 6 inches above the ground while counting aloud by thousands until the law enforcement officer instructs them to put their foot down.

There are four indicators of impairment that the officer will look for during the performance:

  • Swaying
  • Using arms for balance
  • Hopping in order to regain balance
  • Placing the foot on the ground before instructed

Research shows that 83% of individuals that display two or more of these key indicators during testing will have an alcohol impairment over the legal limit.

Using the three field sobriety tests all together provide a 91% accuracy level. On top of these three standardized DUI field sobriety tests, there are several other non-standardized tests that can further increase accuracy. The penalties for a DUI are harsh and with so much at stake, it is vital to have representation in court.

How to Fight Field Sobriety Test Results and DUI Charges

It is the responsibility of the law enforcement officer to ensure that the setting of the field sobriety testing is reasonably dry, level and not slippery. The officer should also make sure that there is enough room and adequate lighting to conduct the tests.

If this is not the case, then the officer should try to move and perform the tests elsewhere, and if they fail to do so this error could be in your favor in court. If the field sobriety tests are not performed in a systemized and reliable manner then there are ways to challenge the accuracy of the results.

Some of the factors that impact the reliability of the tests are:

  • Preexisting physical or mental impairments (over 60 years old, sick, injured, hearing problems, overweight)
  • Brain damage or mental disabilities
  • Movement of the officer (supposed to remain motionless)
  • Suspect wearing unsuitable attire (heels, tight pants, baggy jeans)
  • Officer does not properly time the exercises
  • Environment settings (wet weather, poor lighting, uneven ground, other distractions)
  • Not alcohol related causes for performance failure (medications)
  • Failure of the officer to give adequate instructions

Let Humphrey & Thompson Fight for You

By calling a Bakersfield criminal defense attorney at our firm, you can receive proper representation to protect your rights. We have decades of experience in criminal defense law and can help you through the DUI process and the charges that were the result of a field sobriety test. The penalties for drunk driving are severe, so it is important to obtain experienced legal counsel for your DUI case.

Contact Humphrey & Thompson at (661) 327-1360 if you are in need of an experienced Bakersfield DUI lawyer to fight for your freedom.


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