There are three tests given as part of a standard field sobriety test: the one leg stand test, the walk-and-turn test, and the horizontal gaze nystagmus (HGN) test. Police officers are trained to look for several clues when they request a driver to submit to field sobriety testing. Officers must have current certification in field sobriety testing in order to perform the tests. The instructions must be given exactly the same way each time. If there are problems with the way that the instructions were given, this can raise a reasonable doubt regarding the results of the test.
These tests are administered so that police can gather evidence to support a finding of probable cause for an arrest. The evidence necessary for a finding of probable cause is less than that for a finding of guilt beyond a reasonable doubt at trial. Police must sometimes make quick decisions to arrest an individual that may be intoxicated because they must protect public safety. Sometimes, however, their judgments and observations are not accurate when determining whether or not an individual is intoxicated. It is possible to beat a DWI case by challenging the evidence that the prosecution has against you.
To perform the one-leg-stand (OLS) in a standard field sobriety test, you will be asked to raise one foot approximately six inches off the ground and count out loud for approximately 30 seconds. Your arms must remain at your side during the duration of the test. Indicators for alcohol intoxication include the following:
The problem with this test is that if you have difficulties with your balance under normal circumstances or if you have physical limitations that impair your ability to walk, you can fail the test even if you are not under the influence of drugs or alcohol. Evidence that you were suffering from a preexisting condition that affected your ability to perform the test can help raise a reasonable doubt about your level of intoxication.
The walk and turn test consists of two phases: the instruction phase, where the officer administering the test demonstrates how the test should be performed, and the performance phase, where the subject attempts to perform the test according to the instructions.
To perform the test, you will be asked to take nine heel-to-toe steps along an imaginary line, turn and take nine steps back. You will be instructed to keep your arms at your sides and count the steps out loud while performing the test.
Police look for several clues during a walk-and-turn test, including how well a subject during the test is able to listen to the instructions. Instructions must be given exactly the same way each time an officer administers the test. Police will look for several clues including the following:
The third test typically given during a standard field sobriety test is a horizontal gaze nystagmus test. The investigation officer will hold an object in front of a suspect and ask them to follow the object with their eyes. A nystagmus test is designed to look for involuntary eye movement which occurs when an individual is under the influence of alcohol or other intoxicating substances.
Horizontal gaze nystagmus tests can be inaccurate because many people have conditions that cause them to have natural nystagmus in their eyes which can cause a false positive result on this portion of standard field sobriety testing.
For example, if you were in a car accident and suffered from a head injury in the accident, the symptoms of the injury can cause you to fail field sobriety test even though you were not intoxicated. Police are trained not to administer these tests if you are showing symptoms of a concussion, but sometimes mistakes happen during police investigations. Elderly individuals or those who are overweight can have trouble performing the one leg stand test and the walk and turn test despite not being under the influence of alcohol.
Road conditions can play an important role in making an individual seem as if they are intoxicated according to a field sobriety test even if they are truly not under the influence of any substances. If you were asked to take a field sobriety test on an uneven surface, the accuracy of the walk and turn test and one leg stand test may be challenged. If the horizontal gaze nystagmus test was administered while the police car lights were flashing, this can sometimes interfere with the test by causing nystagmus even if you were not intoxicated.
In many cases, evidence on camera footage from dash cam or body cameras reveals that police failed to give the correct instructions to a DWI suspect asked to perform a field sobriety test. If police failed to provide instructions properly, the idea that the results of these tests are based on standardized research goes out the window, and the accuracy of these tests can be called into question. In cases that involve a refusal to provide a breath, urine, saliva, or blood sample, field sobriety testing may be the state’s primary evidence against a defendant. Successfully challenging this portion of the state’s case can raise a reasonable doubt about an individual’s intoxication.