Orange County Field Sobriety Test Lawyer

FST: Horizontal Gaze Nystagmus Test

Out of all of the field sobriety tests, the horizontal gaze nystagmus test is presumed to be the most accurate. This test is given at a roadside DUI investigation and tests the involuntary twitching of the eyes that occurs when an individual’s abilities are impaired because of the use of alcohol or drugs. Not only can the individual not control the twitching of their eyes, but they are also unaware that the twitching is happening. During this test, the officer will instruct the suspect to follow an object with their eyes as the officer moves the object from side to side. The officer will be looking for the involuntary eye twitch, such as at or before a 45-degree angle, which is a sign of high blood alcohol concentration.

One of the main reasons why this test is not foolproof is because there are several other factors that can contribute to horizontal nystagmus’s, such as head injuries, tired eyes, or simple nervousness.

FST: Walk & Turn Test

The walk and turn test involves splitting the attention of a driver between mental and physical tasks that will indicate impairment. During the test, the officer will be judging how well the suspect can follow and remember directions while performing a variety of physical movements. An officer will typically order the suspect to take nine heel-to-toe steps on a real or imaginary line, pivot around, and then take nine heel-to-toe steps back. The suspect may also be asked to count the steps aloud and keep their arms down.

Some of the clues of intoxication that the Orange County officers look for include:

• Starting to walk too soon
• Stepping off the line
• Losing balance during instructions
• Using arms to balance
• Taking an incorrect number of steps

If a suspect displays two or more of these signs, the NHSTA reports that there is a high chance that the suspect has a BAC of .10% or greater. This test can be significantly more difficult when the ground surface is uneven or poorly lit, or when the officer’s instructions are vague. Additional factors such as the suspect’s weight, physical condition, and if they are injured or ill will also have a substantial impact on the results of the walk and turn test.

FST: One-Leg Stand Test

This test is also a “divided attention” test where the suspect must split their attention and follow instructions correctly. In the one-leg stand test, the officer will instruct the suspect to raise their foot off the ground approximately six inches and to hold still in that position while counting from 1001-1030. The officer will also instruct the suspect to look down at their feet while participating in the test. If the suspect uses their arms to balance, hops, sways, or puts their foot down while trying to balance and follow instructions, there is a high chance that they will be arrested for DUI. The NHTSA estimates that there is a 65% chance that a driver who displays two or more of these clues will have a blood alcohol concentration above .10%.

Similar to the walk and turn test, there are many external factors that can play a role in a suspect’s ability to correctly complete the one-leg stand test. If the suspect is wearing unstable footwear, is fatigued, ill, nervous, or confused about what to do, the test results can be inaccurate. Additional factors such as inclement weather, uneven surface conditions, and vague instructions from the police officer can also distort test results.