Understanding the Importance of Field Sobriety Testing During a DUI Arrest

click for a free consultation
Posted in On December 24, 2012

How Standardized Field Sobriety Tests Impact the Validity of Your DUI Arrest.


As part of almost every single DUI arrest an officer typically will  use roadside Standardized Field Sobriety Testing (SFST) as a way to determine a driver’s level of intoxication. In fact, often times an officer will use the results of those SFST’s as a means for determining probable cause to offer that driver a Chemical Breath Test. As such, it is crucial for an attorney to have a strong understanding of SFST’s, because all too often officers fail to administer them in compliance with their training and in accordance with the standards set forth by the National Highway Traffic Safety Administration (NHTSA). If those SFST’s are not administered per the standards set forth by NHTSA, a judge can conclude that there was no probable cause for the Chemical Breath Test that was submitted to, thus creating the opportunity to have the results of that test deemed inadmissible at trial and/or limited as to how much of an impact that evidence will have on the determination of guilt.
SFST’s are considered “standardized” because NHTSA has demanded that they be administered the exact same way, on every single arrest, and by every single officer determining impairment of a suspected drunk/drugged driver. The courts have also concluded that administering these tests in a uniformed way allows objective observers, mainly judges and juries, the ability to truly and accurately determine levels of intoxication from one impaired driver to another impaired driver. This makes sense, because if these tests aren’t given the same way every time, there is limited validity and/or diminished reliability on the results they produce. Imagine what the result would be if every single doctor took your blood pressure in their own way — without regard to how they were taught in medical school. One doctor creates their own formula by using complex machines to test his/her patient, while another doctor simply takes your pulse with their fingers, counts in his/her head, and guesses as to what the blood pressure reading should be based on previous patients. Wouldn’t this lead to two different methods, with two different results, and no means to compare the two objectively? Of course. The same goes with SFST’s, and the courts agree.
The NHTSA has set forth three SFST’s that all officers are trained routinely in order to be able to administer them. Those three SFST’s are: (1) The Horizontal Gaze Nystagmus (HGN), (2) The 9-Step Walk & Turn, and (3) The One Leg Stand. Each of these tests, as stated earlier, must be administered the exact same way every time. Typically, officers administer these tests in the exact same order as listed above, but circumstances can change that — be it the weather conditions on the road, the lighting, the physical capabilities/disabilities of the person being tested, the training of the officer, the level of suspected impairment of the driver, the availability of assistance from other officers, etc. What most people don’t understand is that any one of those reasons can lead to the tests being administered incorrectly if ignored or overlooked by the officer conducting the tests — especially by inexperienced officers or those that rarely perform SFST.
The Horizontal Gaze Nystagmus, or HGN, is often the first test given by the testing officer. It is considered to be the most scientifically reliable of the three tests as it allows an officer the capability to measure the involuntary “jerking” of the eyes as they move from side to side or as they attempt to focus on a stationary object during the testing by the officer. Nystagmus is a complex concept, but simply put, if you imagine a marble rolling across a table unencumbered, it rolls smoothly without stopping or bouncing. With nystagmus from drugs or alcohol, it’s as if there is sand on the table causing the marble to jerk or bounce as it rolls. Alcohol, and some drugs, act as the sand in that example, causing the eyes to jerk involuntarily as they move side to side, making it impossible for a suspected impaired driver to manipulate the results. From the start of the test the officer is looking for six (6) total clues, taking only four (4) for the officer to determine the test a failure. There are three phases of the HGN test: (1) Lack of Smooth Pursuit, (2) Distinct Nystagmus at Maximum Deviation, and (3) Onset of Nystagmus Prior to 45 degrees. Each phase has two possible clues, one per eye, coming to a total of six (6). Because this test is determined to be the most complex, scientifically significant, and statistically reliable of the tests, this SFST must be precisely given as is laid forth by the NHTSA, otherwise the results can be deemed unreliable and inadmissible. Moreover, it is important to have a lawyer that understands and has been trained in SFST’s because there are multiple other reasons why someone might display nystagmus in one or both of their eyes, be it for medical reasons, physical limitations, medications, contacts, head trauma, etc.
The second test is the 9-Step Walk and Turn. The 9-Step Walk & Turn is a relatively difficult test to pass, even when someone is not impaired, so it can often be the easiest to attack in court. Furthermore, it has less of a scientific foundation, and has a significantly lower reliability in determining impairment. Nevertheless, this is the test many have seen on TV where you see a suspected driver walking down a straight line, touching heal to toe, walking nine (9) steps, turning at the end, and then walking back. During this test the officer is looking for eight (8) total clues, and it takes only two (2) to fail. The officer is evaluating a suspected driver for the following clues: (1) the person cannot keep balance while listening to the instructions, (2) the person begins before the instructions are finished, (3) the person stops to regain balance, (4) the person does not touch heel-to-toe, (5) the person steps off the line, (6) the person uses their arms to balance, 7) the person makes an improper turn, and, finally, (8) the person takes an incorrect number of steps. Often times this test is administered incorrectly, and a failure can come down to a few inches — be it the person’s feet are determined to be too far apart, they raise their hands too high to regain balance, or they step a few inches off of an imaginary line. Many officers don’t know the fine details and allowances within each phase of this test — putting the person down as having failed, when, in all actuality, they were within the margins allowed to be considered passing. Someone’s results may also be thrown off due to physical impairments that the officer didn’t account for as well. All of this must be considered by a lawyer who truly understands the proper procedures for administering the 9-Step Walk and Turn.
Finally, The One Leg Stand is typically administered by the testing officer. This test is also a relatively difficult test to pass, even while sober. As such, a determined failure on this test can be challenged at trial or in front of a judge during a suppression hearing. Furthermore, this test also has even a lesser scientific foundation, and has a significantly lower reliability, as compared to the other two tests in determining impairment. A testing officer is looking for four (4) total clues, taking only two (2) to label someone as having failed. Those clues are as follows: (1) the person sways while balancing, (2) the person uses their arms for balance, (3) the person hops to maintain their balance, and (4) the person puts their foot down. This test, like the 9-Step Walk & Turn, can come down to inches and a few simple questions. Did the person raise their arms just a few inches too high? Does the officer know the threshold for what is too high? Did the officer give the defendant a choice as to what foot they could use? Did the officer ascertain any physical limitations the person taking the test might have? All of these questions are crucial in determining if, in fact, a person truly is impaired, and if that person truly failed this third SFST.
As is very clear, SFST’s, if not performed in a standardized way, can lead to bad results and inadmissible results. Given the complex nature of SFST’s and the absolute necessity of them to be administered correctly, it is essential that you hire an attorney that has been trained in administering them, and someone that can spot when they haven’t been done appropriately. Banks & Brower, LLC was formulated by two attorneys that spent years prosecuting solely DUI cases. If you hire the Indianapolis Criminal Defense Attorneys at Banks & Brower, you can rest assured you have a law firm on your side that completely understands the nuances of every single DUI case, including the administration of SFST’s.