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Unreliability of Horizontal Gaze Nystagmus test during a DUI investigation

June 22, 2016

Horizontal Gaze Nystagmus

This article discusses the Unreliability of the Horizontal Gaze Nystagmus test during a DUI investigation. Click on the links below to go directly to your topic of interest.

HGN: HORIZONTAL GAZE NYSTAGMUS
NHTSA RESEARCH INTO HGN
PROBLEMS WITH NHTSA HGN RESEARCH
ADMINISTRATION OF HORIZONTAL GAZE NYSTAGMUS
RECENT RESEARCH: HORIZONTAL GAZE NYSTAGMUS
HORIZONTAL GAZE NYSTAGMUS STUDY

HGN: HORIZONTAL GAZE NYSTAGMUS

One of the most common arrests in Los Angeles County is a DUI. If you are investigated for a DUI, the DUI investigating officer may ask you to submit to field sobriety tests. The field sobriety tests are a series of tests that are supposed to help an officer during a Los Angeles DUI investigation to determine if the driver is under the influence of alcohol. The most commonly used FST tests (and the ones approved by NHTSA) are known as “Standardized Field Sobriety” tests and are the One Leg Stand (OLS), Walk and Turn (WAT), and Horizontal Gaze Nystagmus (HGN). Because NHTSA conducted research and approved those three tests, they are, Standard Field Sobriety Tests (SFST), which means that they are conducted the same way every time. The NHTSA concluded that the One Leg Stand Test, Walk and Turn Test, and Horizontal Gaze Nystagmus Test are the most reliable tests to determine impairment. After NHTSA adopted the tests, the CHP and many other police agencies are not use these three tests during their Drunk Driving Investigations in Los Angeles

NHTSA RESEARCH INTO HGN

Most law enforcement, when it comes to DUI in Los Angeles, trust the National Highway Traffic Administration, known as “NITSA” (and abbreviated as NHTSA) in their DUI research. The NHTSA paid for and wrote a book on how to do a DUI investigation. The research was done in the 1970th and at that time, due to the permissible level of alcohol during driving being higher, tried to determine if a DUI driver is below or above the Legal Blood Alcohol Level of 0.10%. The NHTSA used the horizontal gaze nystagmus test as one of the “standardized” field sobriety tests because it was supposed to be administered in specific ways and was validated in 1975. The 1975 experiment tried to determine how accurately police officers can approximate the number of people who would be above .10% BAC or under the influence of alcohol.

The remaining two NHTSA standardized tests were chosen to be the Walk and Turn Test (WAT) and the One-Leg-Stand Test (OLS). Subsequent to the 1975 experiments, the findings were confirmed with additional “validation studies” in 1995, 1997, and 1998. The California Highway Patrol manual states that the use of three standardized (HGN, OLS, and WAT) tests will allow CHP officers to determine with 90% accuracy if someone is under the influence of alcohol. For defense, having a police officer conduct standardized field sobriety tests can be a major challenge because of its perceived accuracy.

However, Los Angeles DUI Attorney can successfully argue that the NHTSA study and the validation studies are inaccurate because they produce a lot of false positives during a Los Angeles DUI investigation. As another problem with the NHTSA study is the NHTSA research was done by psychologists who did not use control groups – a practice that would not be approved by current standards of scientific research and especially not good enough when a person’s life is on the line, such as after a DUI conviction. Also, blood alcohol level results obtained by analyzing blood is a more direct and therefore is more reliable way to measure the actual level of alcohol in a person’s body. However, during the NHTSA study, no blood samples were taken, instead, NHTSA relied on breathalyzer results to determine blood alcohol levels. While it is an acceptable substitute in some contexts, a scientific study should rely on the most accurate data, and relying on a breathalyzer is not the most reliable data. Breath alcohol results are often inaccurate especially if a breath sample is provided within a short time of consumption of alcohol and can overstate the blood alcohol level by as much as 40%.

PROBLEMS WITH NHTSA HGN RESEARCH

Subsequent studies show that NHTSA research is not reliable. Ever since this 30-year-old, and arguably poorly done study by NHTSA was conducted, other research questioned the reliability of NHTSA standardized field sobriety tests, including Horizontal Gaze Nystagum. Los Angeles DUI and Criminal Defense Attorney believes that Los Angeles DUI Law Enforcement should not rely on Horizontal Gaze Nystagmus at all to determine if a driver is under the influence of alcohol. The scientific research Los Angeles DUI Attorney saw points out that HGN only shows the presence of alcohol and cannot be correlated to a specific level. But the prosecutors will continue to rely on the HGN and other Standardized Field Sobriety Tests to accuse drivers of DUI and to obtain conviction even when the science shows otherwise.

If you are arrested for a DUI in Los Angeles, we recommend talking a Los Angeles DUI attorney to get help and understand how you can win your Los Angeles DUI case. We can provide help of an experienced DUI attorney to convince the prosecution that the DUI investigation was poorly done and that the tests are not reliable. Los Angeles DUI attorney will ask the court or the prosecutor to dismiss all charges in your DUI case. Presently, the Horizontal Gaze Nystagmus test is the most widely applied procedure in United States law enforcement for detecting alcohol impairment during DUI investigation and especially during Los Angeles DUI investigation field sobriety testing. The prosecutors will think that the Field Sobriety Testing is equivalent to chemical testing or breath or blood for the presence of alcohol.

Los Angeles DUI attorney tries to explain here that the Horizontal Gaze Nystagmus (HGN) is not as reliable as NHTSA claims it to be.

In Los Angeles DUI courts you will need the help of a DUI Los Angeles Attorney to get the dismissal of your DUI case based in part on the unreliability of the Horizontal Gaze Nystagmus test.

ADMINISTRATION OF HORIZONTAL GAZE NYSTAGMUS

Nystagmus

Horizontal Gaze Nystagmus is an involuntary jerking of the eye associated with the consumption of CNS depressants (such as alcohol). What an officer investigating DUI looks for when he shines a flashlight and holds a pencil is that jerking. The jerking is supposed to increase with a higher level of alcohol in the blood.

To properly administer the test, a Los Angeles DUI officer needs to

(1) clearly observe the eye;

(2) properly instruct the driver;

(3) hold a finger, a pen (or a stylus) 12-15 inches from the face of the driver and slightly above the eye level.

The instructions that an officer provides to a person suspected of a DUI are simply to follow the stylus (or pen) with eyes only and without turning their head. The officer must inform the driver suspected of a DUI that he will “check his/her eyes”.

The officer will look for 6 validated clues to determine if a person is impaired (3 in each eye). If 4 out of 6 clues are present, the test, according to NHTSA, is considered to be 77% accurate in determining that a person is above a .10% BAC level. The case law, however, does not allow an officer to testify that the presence of HGN (horizontal gaze nystagmus) can be correlated to a specific alcohol level (People v. Loomis). Also, a 77% accuracy means that 23% of people (or almost 1 in every 4 people) will not be under the influence of alcohol even when they have all 6 clues. For example, the presence of nystagmus can be evidence of a neurological condition. Also, some people have nystagmus completely unrelated to alcohol consumption and unrelated to any medical condition.

HERE ARE THE 6 CLUES (3 for each eye).

(1) Lack of smooth pursuit;

(2) distinct and sustained nystagmus at maximum deviation; and

(3) onset of nystagmus prior to 45 degrees.

Medical literature criticizes the Horizontal Gaze Nystagmus test on the side of the road because various medications (even if not affecting driving), diseases, and congenital reasons can cause HGN. This is especially true when the test is conducted by an officer who is experienced and only completed a short course on DUI investigations.

RECENT RESEARCH: HORIZONTAL GAZE NYSTAGMUS

Recent studies concluded that 95% of DUI enforcement officers improperly conduct HGN and wrongfully place drivers under arrest.

POLICE OFFICER ERRORS IN THE ADMINISTRATION OF HGN:

(1): Not holding the stylus within proper distance from the driver’s face.

(2): The light from police cars or other vehicles interferes with testing (and actually causes the nystagmus).

(3): The test is done too fast. According to the NHTSA manual, the test should take no less than 84 seconds and consist of 14 passes in total with 7 for each eye. In total, each eye is measured 4 times measuring (a) equal tracking (b) smooth pursuit (c) maximum deviation (d) onset angle of nystagmus. The determination of equal tracking is done 1 time; however, the other 3 tests are done twice to confirm the results.

(4): the officer does not do the test the correct number of times (see above). Most officers do nystagmus 1 time from center to right and 1 time from center to left. This violates NHTSA guidelines which require 7 passes for each eye.

An officer who conducts a horizontal gaze nystagmus test is required to be trained in the administration of the test. If the test is not performed according to the standard criteria, the test can not be deemed valid. During the nystagmus test, the subject of the test should take his glasses off and the stimulus used to administer the test should be kept at 12-15 inches from the nose of the subject. If the officer does not follow these instructions, the test will be invalid because it violated the original test instructions. During the nystagmus test, the officer will attempt to observe the tracking ability of the eyes and the size of the pupils. Also, the officer will note any lack of smooth pursuit, if the distinct nystagmus is present at the maximum deviation, and if the nystagmus starts prior to the 45% angle.

HORIZONTAL GAZE NYSTAGMUS STUDY

A 2010 study published in a journal of Investigative Ophthalmology and Visual Science (May 2010 issue, Volume 51, No. 5) debunked the value of HGN by pointing out that:

it is present in more than 50% of the population;
it is more likely to be present when the person is fatigued;
it can be pathological and the difference with physiological HGN can’t be determined by an officer on the side of the road;

That study addressed law enforcement reliance on one of HGN cues, “onset prior to 45 degrees”. The study concluded that horizontal gaze nystagmus was present in:

10 degrees angle in 21% of subjects;
20-degree angle in 34% of subjects;
30 degrees angle in 43% of subjects;
40 degrees angle in 73% of subjects;
42.7 degrees angle (maximum in the study) has HGN present in 93% of subjects;

A previous study by Abel in 1978 only had one person show HGN at 20 20-degree angle. This 2010 study by Chad Whyte, Anne Marie Petrock, and Michael Rosenberg showed a much higher occurrence of HGN in the general population and indicated that “most of their subjects (who were all sober) would fail HGN test in the field. NIHTSA has to either redo its study or suspend its recommendation of HGN usage for law enforcement. Until that happens, you will need the help of our expert Los Angeles DUI lawyers to defend against junk science used by police.

If you are arrested for a DUI, please call (818) 921 7744 DUI Attorney Los Angeles to talk to someone who is qualified to help you defend your case. Los Angeles DUI attorney is known for his dedication to his clients and his ability to get the best results for his clients in the most desperate situations. We offer great payment plans and can help you not only in court but also at the DMV. Our top Los Angeles DUI lawyer is able to provide quality defense at an affordable price.