Extensive studies have been conducted on field sobriety tests, usually called SFSTs. According to this research, police officers with the right training can identify impaired operators over 90 percent of the time by using these tests. However, this assumes that the officer conducted the tests correctly, evaluated results properly, and there are no intervening factors. Of course a Kansas City DUI lawyer will need to see the results of these tests and the way that they were conducted.
DWI Lawyers and Field Sobriety Tests
There are three distinct tests that are used. The tests are used by officers to determine if operators are impaired and if they have probable cause to make an arrest.
This is a brief description of these three tests:
Horizontal gaze nystagmus: Usually called HGN, this test allows the officer to observe if the operator’s eyes will move involuntarily when an objects moves from side to side. This test has been shown to detect an impairment about 77 percent of the time. It can also detect impairment by certain drugs beyond impairment by alcohol.
One-leg stand and walk-and-turn tests: These two tests measure certain activities that most sober drivers should be able to do with ease. The operator has to pay attention and follow certain instructions. They also have to perform physical movements that should be simple.
Both of these tests are called divided attention tests because they require the driver to divide their attention between what should be simple physical and mental tasks.
In the walk-and-turn exam, the operator simply has to take nine steps in a prescribed manner, turn around on one foot, and then retrace their path back. Apparently, this test has proven 68 percent effective in determining impairment.
For the one-legged test, the subject has to count with one leg held six inches off of the ground. The officer looks for certain indications of impairment, and these tests have been proven to be about 65 percent effective in determining impairment.
How Effective Are Field Sobriety Tests?
Research has confirmed that these tests as more effective than not. However, none of them are 100 percent effective. In some states, they may be admitted as evidence in a DWI case, but failing one or more of these tests is no guarantee of a DWI conviction.
These are some problems with sobriety tests:
* Other physical or mental conditions might make it impossible for subjects to complete the tests, and these might not have anything to do with impairment or the ability to drive a car.
* In addition, officers might not be trained to conduct these tests properly or even evaluate the results of the tests when they do conduct them properly.
In other words, these tests can be subjective and not objective measures of driving impairment. The job of a DWI attorney will include evaluating the way the tests were conducted and the way that the police officer evaluated the results. Because the tests are imperfect, they may be allowed as probably cause but not a measure of guilt.