Call For A Free Initial Consultation (703) 273-4100


What are DUI Field Sobriety Tests?

Posted by Jeremy S. Letnick | May 30, 2015 | 0 Comments

What are Field Sobriety Tests?

DUI Field Sobriety Tests (FSTs) are a battery of tests developed by the National Highway Traffic Safety Administration (NHTSA) in an effort to provide police officers with a method to determine impaired driving.  However, they are not perfect by any means and are certainly not 100% accurate.  They are a tool that, at least in theory, should help police officers take drunk drivers off the road for the safety of the general public.  Due to the depressant nature of alcohol on the central nervous system, these tests offer a way for police officers to examine an individual's physiological response to alcohol and their ability to follow directions.


Horizontal Gaze Nystagmus (HGN)

HGN is an involuntary jerking of the eye that occurs naturally when the eyes are rotated at certain angles. Specifically, the Horizontal Gaze Nystagmus is an involuntary jerking of the eye that occurs naturally as the eyes gaze to the side. This nystagmus is exaggerated when alcohol is in the system to the point of impairment. As a result, the jerking of the eye occurs at lesser angles than those in which there is no alcohol in the system. Essentially, the individual will follow a moving object, such as a pen or officer's finger, horizontally with his or her eyes.  The officer looks for three indicators of impairment:
a) lack of smooth pursuit,

b) clear jerking of the eye at “maximum deviation, and

c) if the angle of onset of jerking is within 45 degrees of center. If, between the two eyes, four or more clues appear, the suspect likely has a BAC of 0.08 or greater.

The accuracy of the HGN test is a bit higher than the other field sobriety tests – 77% when the first test was conducted in 1981.  The accuracy went up to 88% in 1998 in large part due to the police officers' substantial increase in experience in deploying the tests.  Indeed, this test is the preferred test for police officers on scene because it gives them an idea as to an individual's level of impairment and a gymnast, for example, cannot “outperform” this test.

However, many courts do not allow the Horizontal Gaze Nystagmus into evidence since there are many medical reasons that individuals may display such involuntary jerking of the eyes that are unrelated to alcohol consumption and, quite frankly, the arresting police officer is not a doctor.  As a result, many courts will either not allow the results into evidence or, in the alternative, allow the procedure of the test into evidence but merely to show only whether the individual followed directions.  Did they keep their head still as instructed?  Were they talking during the test when ordered to remain quiet?  Did they remain balanced while they followed the officer's pen or finger?  In any event, an officer's opinion as to whether they showed signs of alcohol impairment should never be allowed into evidence since such an opinion infringes on the court's determination of impairment (which is the court's directive).

Walk and Turn Test

The Walk and Turn test is a 9-step test where the individual is required to have a divided attention. It is generally understood that those who are impaired have a more difficult time following simple instructions and dividing their attention. In this test, the individual is required to take nine steps, heel-to-toe, along a straight line. After taking the steps, the individual must turn and “pivot” to face the opposite direction. During this 9-step process, the officer looks for eight indicators of impairment: if the suspect cannot keep balance while listening to the instructions, begins before the instructions are finished, stops while walking to regain balance, does not touch heel-to-toe, steps off the line, uses arms to balance, makes an improper turn, or takes an incorrect number of steps.

The accuracy of the Walk and Turn test was 68% when the first test was conducted in 1981.  The accuracy went up to 79% in 1998 again due in large part to the police officers' substantial increase in experience in deploying the tests.  This test is substantially vulnerable to challenge as many individuals have prior leg and hip injuries that may preclude them from passing the test whether or not they are impaired.

One-Legged Stand test

The One-Legged Stand test is a balance and attention test where the individual is instructed to stand with one foot approximately six inches off the ground and count aloud until told to put the foot down. The officer times the subject for a period of time, typically for 30 seconds. The officer looks for four indicators of impairment, including swaying while balancing, using arms to balance, hopping to maintain balance, and putting the foot down.

The accuracy of the One-Legged Stand test was 65% when the test was conducted in 1981 and 83% in 1998.  This test is also vulnerable to challenge due to preexisting injuries the individual may have that may preclude their ability to pass the test.

Other Field Sobriety Tests (Not Recommended by NHTSA)

Alphabet Test

Many officers upon smelling an odor of alcohol will have the individual remain in their car and check whether they can complete this “easy” task.  They will generally have the individual count from a random letter, through the alphabet, stopping at another letter (e.g. H-X).  Other times, the officer will require the individual to successfully do the alphabet backwards.  This test is an attention test to see if the individual's cognitive faculties are functioning properly.  This test simply confuses many people and can be unfair at times.

Finger Dexterity Test

In this test, the individual will be required to count on their fingers using their thumb to touch the other fingers on their corresponding hand in a manner of 4-3-2-1 generally starting with their pinky finger moving through their fingers ending on their thumb.  Subsequently, they must then go back from their thumb to their pinky by generally proceeding by 1-2-3-4 for however many times the officer instructs.  This test, of course, is ridiculous and is intending to check the individual's attention to detail and motor function.

Counting Test

The officer will ask the individual to count starting from an arbitrary number and ending on an arbitrary number (e.g. 61-101).  This test is designed to test an individual's attention.  Many people do not successfully complete this test and will start at the correct number but will forget the ending number and generally go too far.

Finger-To-Nose Test

This test is simply designed to test an individual's motor function.  The more impaired an individual is the more likely they cannot perform the simple function of touching their nose (and may touch their cheek instead).

Challenging Field Sobriety Tests

A good lawyer will remind the court that these are not perfect conditions under which the individual is taking these tests.  Many individuals are required to take these tests on the side of the road, in the middle of the night, with a police officer displaying their badge of authority examining them.  Many people are tired as it is generally late and are nervous and scared.  As a result, their failure to pay attention to detail should be given some credit due to these conditions.

In terms of the Horizontal Gaze Nystagmus Test, are there any medical conditions that may result in an involuntary jerking of the eye?  Does the individual have diabetes?  Do they have an eye disorder?  Was it pitch black outside and difficult to examine the eye?  Is the officer a doctor?

As indicated previously, the Walk and Turn test and One-Legged Stand test are more easily subject to challenge.  Were these tests conducted on the side of the road?  If so, was it a major highway with cars whizzing by at a high rate of speed?  What kind of shoes was the individual wearing?  Flats or heels?  Sometimes a female may be wearing heels and the officer may try to “help” and have her take these tests barefoot.  Was she then walking or standing barefoot on pieces of gravel?  Was it cold out and, if so, was the individual wearing a jacket (and not shivering from the cold)?  For the walk and turn test, was it an imaginary line they were required to walk?  If so, how can it be determined if they stepped off-line?  Preexisting physical medical conditions?

In Virginia, there is case law by dicta that says that Field Sobriety Tests should be consensual.  As a result, if the officer told the individual they had to take these tests, there is a constitutional argument that their consent was overborne by undue police influence and, therefore, the tests should not admissible against them.

Should I Take the Field Sobriety Tests?

Generally, it is not recommended to take the Field Sobriety Tests due to the subjective viewpoint of the officer.  Many people feel they passed the tests when, in reality, there were multiple “clues” of intoxication that may make it difficult to challenge the case.  At the Letnick Law Firm PLC, we have had individuals fail the field sobriety tests and the officers arrest the individual and bring them in for a blood test.  Weeks later the blood results are back and there is no alcohol or drugs in the system.  As a result, the individual spent a night jail, had their vehicle towed, lost their license administratively (by statute), and incurred a charge on their record…for nothing.  Of course, if you refuse the Field Sobriety Tests, you may be arrested for DUI in any event.  However, when you appear for court, your lawyer will be in a much better position to argue you were not driving while impaired since there is no evidence of impairment aside from, perhaps, speeding which many people get tickets sober, right?

Do I Need a Lawyer for a DUI?

If you or someone you know has been charged with DUI, make sure a lawyer is contacted.  See the DUI section of our website for more information about DUIs and do not hesitate to contact us for more information.  We regularly appear in Fairfax County, Prince William County, and Loudoun County.  If you are charged with DUI in another jurisdiction in Virginia, feel free to contact us and we will refer you to a competent lawyer in that jurisdiction to help you in your case.  A DUI is a serious matter and you need to be informed.  Mothers Against Driving over the past ten years has put tremendous pressure on the Virginia courts to prosecute DUIs and a lawyer will be your most important tool in your case.

About the Author

Jeremy S. Letnick

Jeremy Letnick is in the courtroom daily. Raised by both an attorney and a Fairfax County Police Officer, Mr. Letnick has been exposed to the intricate workings of both sides of the legal system his entire life.  His focus is criminal law and traffic law.  As result, he has the distinction of regularly appearing in the courts of Northern Virginia and consistently appears in front of the Judges and routinely works with the Prosecutors and Police Officers.  He has handled thousands of cases ranging from simple speeding tickets to robbery and manslaughter charges.  Mr. Letnick's ultimate goal is to make the client's court experience as stress-free as possible while pursuing the client's objectives.  Mr. Letnick is a second-degree black belt and takes the respectful position that everyone should stand up for themselves in Court and in life. George Mason University, B.A. 2004Thomas M. Cooley School of Law, J.D. 2008Certificate of Merit “Book Award”:Trial SkillsAlternative Dispute ResolutionForensic ScienceFairfax Bar AssociationPrince William Bar Association


There are no comments for this post. Be the first and Add your Comment below.

Leave a Comment

The truth about your case

We will not “sugar coat.” We will tell you exactly what you are facing and will give you the best and worst case scenarios. We are not here to scare you or to pull the wool over your eyes. We find many people calling us for a simple case where they have spoken to other lawyers and are now afraid. However, after speaking with those people and getting the facts, many times there is nothing to fear. We will tell you how things look and we will tell you the truth because we want happy clients. That’s you!

Letnick Law Office
(703) 273-4266 (fax)
Mon: 08:30am - 05:00pm
Tue: 08:30am - 05:00pm
Wed: 08:30am - 05:00pm
Thu: 08:30am - 05:00pm
Fri: 08:30am - 05:00pm