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Even if you’ve never taken one before, most people are familiar with the Breathalyzer test. Police officers may administer a Breathalyzer test after pulling over a driver suspected of drunk driving, but only if there are reasonable grounds to do so. Since an officer must have “reasonable suspicion” in order to administer this test, other preliminary tests must be performed prior to the Breathalyzer. These preliminary tests are referred to as field (or “roadside”) sobriety tests.


The Tests Before the Breathalyzer


If you’re pulled over for a suspected DUI, there are a number of things you might have to do prior to taking a Breathalyzer test.


Being pulled over under reasonable suspicion of drunk driving will begin much like any other time you’re stopped by the cops—the officer will approach your window and ask to see your license and registration. Then, if the officer notices something that suggests that the driver may be under the influence of alcohol (for instance, slurred speech or the smell of alcohol), the officer will typically administer a field sobriety test, which generally consists of three components:


  1. Horizontal gaze nystagmus (HGN). Horizontal gaze nystagmus is a natural, involuntary jerking of the eye that occurs whenever you move your eye from side to side. The HGN test examines your eye movement, since the jerking is noticeably exaggerated when someone is under the influence of alcohol.

While performing this test, an officer may shine a flashlight into your eye to watch the motion of your eye. According to the National Highway Traffic Safety Administration, there are three specific indicators that imply impairment: “if the eye cannot follow a moving object smoothly, if jerking is distinct when the eye is at maximum deviation, and if the angle of onset of jerking is within 45 degrees of center.”

  1. Walk-and-turn (WAT). The WAT test is a simple test of coordination and ability that any sober person should be able to complete without a problem. It requires that the driver take nine steps forward in a straight line (heel-to-toe), turn on one foot, and then return to the starting point in the same way.
  2. One-leg stand (OLS). The OLS test is perhaps the goofiest-looking of all. It requires the driver to stand on one foot and count for 30 seconds. If the driver stumbles, falls, sways significantly, or is completely unable to stand on one foot at all, the officer may take that as an indicator of intoxication.


While these three are the most common components to a field sobriety tests, there are other things that a driver may be asked to do, including: reciting the alphabet, touching your finger to the tip of your nose, and tipping your head backwards while standing upright.


Together, these three tests are considered more than adequate indicators of impairment. Unfortunately, they are incredibly subjective tests, completely based on the opinion of the arresting officer.


If a driver fails the field sobriety test, he or she will be given a Breathalyzer to test their blood-alcohol content. If the Breathalyzer indicates a BAC of .08 or higher, it will be considered probable cause and the driver can be arrested on the spot.


DUI Attorney Denver

Build Your Defense


Despite the acceptance of both field sobriety tests and Breathalyzer tests, sometimes mistakes are made. A qualified DUI lawyer knows where to look for weaknesses in arrests based only on these tests and may be able to present a credible defense for you if you facing a DUI charge.


If you’re facing a DUI charge, contact a smart, experienced attorney today, because the sooner you start building your case, the more likely you are to have a positive outcome.


About the Author:

Kimberly Diego is a criminal defense attorney in Denver practicing atThe Law Office of Kimberly Diego. She obtained her undergraduate degree from Georgetown University and her law degree at the University of Colorado. She was named one of Super Lawyers’ “Rising Stars of 2012” and “Top 100 Trial Lawyers in Colorado” for 2012 and 2013 by The National Trial Lawyers. Both honors are limited to a small percentage of practicing attorneys in each state.  She has also been recognized for her work in domestic violence cases.


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