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Friday, August 23, 2013

DUI Sobriety Testing Explained

By: Sean Farrelly

I have previously written about what to expect if a police office suspects that you may be driving under the influence.  A major part of any DUI investigation is the administration of what are known as the Standardized Field Sobriety Tests. These tests, commonly referred to by law enforcement as SFSTs are a series of tests designed by the National Highway Traffic Safety Administration in order to aid law enforcement in their assessment of whether an individual is operating a motor vehicle with a blood alcohol content above the legal limit.  Validation studies indicate that if administered properly by a trained law enforcement officer, the tests can accurately predict around 80-90% of the time whether someone's blood alcohol content is above the legal limit.  As the numbers indicate, these tests are by no means infallible, and when administered incorrectly (which is often the case) or by inexperienced officers, the accuracy of the tests is much lower.  Even when administered perfectly by a seasoned veteran, the results of this test do not support a definitive determination that an individual is guilty of DUI.  In fact, the training manual provided during the certification course for SFSTs clearly states that these tests are designed to aid an officer in determining whether there exists a basis to make an arrest, not whether someone is ultimately guilty.  

The SFSTs include three tests, the Horizontal Gaze Nystagmus Test, known as the HGN Test, the Walk and Turn Test and the One Leg Stand Test.  Each of these tests requires very specific and very technical instruction and each test is looking for different signs of impairment.  Each test has a specific number of "clues" the administering officer is looking for.  When a suspect exhibits a clue, it gives the officer more reason to believe they are impaired.  There are six possible clues on the HGN Test, eight possible clues on the Walk and Turn Test, and four possible clues on the One Leg Stand.  A suspect "fails" HGN if they exhibit four out of six clues, Walk and Turn if they exhibit four out of eight clues, and One Leg Stand if they exhibit two out of four clues.

The HGN Test determines whether your eyes display signs of nystagmus.  Nystagmus is defined as the involuntary jerking of an eye.  Nystagmus can be caused by any number of things, flashing lights, head trauma and pre-existing medical conditions can all cause nystagmus.  However, impairment by alcohol and certain types of drugs can also cause an individual to display nystagmus.  During the HGN test, the officer will look for nystagmus by employing three different methods, they are known as lack of smooth pursuit, onset of nystagmus prior to forty five degrees and distinct and sustained nystagmus at maximum deviation.  Without going into too much scientific detail, each method can expose nystagmus in a different manner and the combination of all three methods paints a very clear picture for the administering officer.  The six clues for the HGN test comprise the three methods for detecting nystagmus when display ed in both eyes (3 methods x 2 eyes = 6 clues for all you non math majors).  The HGN Test is the most technical and scientific of the three tests and most often is the test that is administered or interpreted incorrectly.  However, if administered properly this test is generally the most accurate predictor of impairment.

The Walk and Turn Test is what is known as a "divided attention" test.  This test requires the suspect to listen to a number of instructions while simultaneously complying with the previous instructions given.  The point of this test is to both test an individual's motor skills while also testing their ability to comprehend and process multiple thoughts and commands at the same time.  This test is designed to force an individual to utilize the same brain functions and motor skills necessary to safely drive a car.  The instructions require an individual to walk 9 steps down an imaginary line, those steps should all be "heel to toe" with no space in between the feet.  After taking the 9 steps, the suspect is instructed to make a very specific 180 degree turn and then walk back in the same manner.  The eight clues on this test are failure to maintain balance during instructions, beginning test before instructed to do so, stopping while walking, failing to touch heel to toe, stepping off line, using arms to balance, improper turning and taking the incorrect number of steps.  As you can see, some of these clues are meant to test an individual's motor skills and some are intended to test an individual's thinking skills.  This test has some marginal value as an indicator of impairment, but the problem is that a lot of the clues are subjective and also a lot of people who have some sort of pre-existing medical condition or are elderly or are simply clumsy would struggle with this test whether they are sober or drunk.  

The One Leg Stand Test is self-explanatory.  The test requires you to hold one foot off the ground, kep your arms at your side and maintain balance for 30 seconds while counting out loud.  The clues on the One Leg Stand Test are swaying, using arms to balance, hopping or putting your foot down before 30 seconds.  This test is similar to the Walk and Turn Test as it is flawed for the same reasons.  A large percentage of individuals can't hold their foot off the ground for 30 seconds without support even if they are sober.  

So there it is, SFSTs in a nutshell.  Even though I am a DC DUI defense lawyer, I won't sit here and say these tests have absolutely no redeeming value.  They were developed over a long period of time by a reputable government agency and they are based in scientific validity.  However, the major problem lies not in the tests themselves, but in the administration of the tests.  Unfortunately, there are very few police officers in DC who have the knowledge and the experience to properly administer the tests.  Although all officers who administer the tests during a DUI investigation are certified to administer the tests, this certification absolutely does not mean the officer knows what they are doing.  Officers are pushed through the 40 hour certification course and often become certified with no real ability to properly administer the tests.  

That is why it is so important to hire a DUI defense attorney who understands the SFSTs from top to bottom.  An excellent DC DUI defense attorney will be very effective when cross examining a police officer who did a poor job administering the SFSTs.  Often it is the testimony of the officer who performed SFSTs that will determine whether an individual is convicted so ensuring that a judge or jury is aware of their incompetence is critical.

Please contact Farrelly PC if you have been arrested for DUI in order to discuss the facts of your case and what to expect moving forward.

 


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