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Understand the finer points of a field sobriety test

On Behalf of | Dec 18, 2017 | Drunk Driving Defense

People who are pulled over because an officer thinks that they might driving drunk will usually be asked to take tests to determine if they are intoxicated. One of the options that might come into the picture is a field sobriety test.

The field sobriety test doesn’t give the officer an actual blood alcohol content percentage. Instead, it only provides the officer with a way to determine if the person’s movements and other clues point toward a likely intoxication.

Types of tests

There are only three tests that fall into the standardized field sobriety test. These are the walk-and-turn, the horizontal gaze nystagmus test, and the one-leg stand. No other tests are included in this battery of tests.

Some officers aren’t trained to do the standardized field sobriety test so they rely on other tests to make the determination about whether a person is intoxicated. Some of the tests that are done include having you say the alphabet backwards or do other exercises.

Overview of the tests

The one-leg stand requires the person who is taking the test to stand on one foot for 30 sections. The officer is watching for trouble with balancing, which could indicate intoxication. The issue with this is that some people, such as those who have an inner ear problem, might have difficulties with this. Even some elderly people might have trouble.

The walk-and-turn test requires the person to walk heel-to-toe in a straight line. The person has to turn around and walk back. The officer looks for eight signs of impairment during this process. This is another test that can be impacted by health implications.

The horizontal gaze nystagmus test evaluates the movements of eyes. Involuntary jerking can signal impairment. The officer who is conducting the exam looks for three indicators that can show a person is intoxicated.

The problems

While these tests are fairly accurate, there are some instances in which they might not be. Overall, this battery of tests is around 91-percent accurate. Considering the acceptance of some false positives, the accuracy rate increases to 94 percent.

In almost all cases, the field sobriety test is the first test that is done. People who don’t pass will usually be asked to do another test to determine the blood alcohol concentration. If this is found to be at or above the legal limit, the person will be arrested for drunk driving. This means he or she needs to get moving on a defense strategy right away.

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