What is the HGN test for a DUI?
Horizontal Gaze Nystagmus (HGN) Field Sobriety Test One of the standardized field sobriety tests (FSTs) used by law enforcement for a DUI arrest is the Horizontal Gaze Nystagmus (HGN) Field Sobriety test, often abbreviated as the HGN FST.
What is the horizontal gaze nystagmus test (HGN)?
One of the standardized field sobriety tests (FSTs) used by law enforcement for a DUI arrest is the Horizontal Gaze Nystagmus test, often abbreviated as the HGN Field Sobriety Test.
How does the HGN test work?
How The HGN Test Works. Two types of twitching. There are really two types of Nystagmus: (1) Alcohol Gaze Nystagmus (AGN) which is commonly used for HGN testing and in which the eyes move but not the head, and Positional Alcohol Nystagmus (PAN) in which the eyes and head both move.
How reliable is the HGN test in California?
In California, the HGN test is considered a reliable and valid testing procedure.14Hence, HGN test results may be admitted in evidence to corroborate or attack the allegation that a particular defendant had been driving under the influence of alcohol.15
How accurate is the HGN?
77% reliableAccording to the National Highway Transportation Safety Administration (NHTSA), studies have revealed the HGN Test to be 77% reliable in determining whether a driver has a blood alcohol concentration above .
How many clues do you need to fail HGN?
There are six possible clues that an officer can claim indicate impairment on the HGN test. (Three clues per eye) It only takes two clues out of the six possible to “fail” the HGN test.
Which field sobriety test is most accurate?
Tests sponsored by the National Highway Traffic Safety Administration revealed that the HGN test is most reliable (77 percent), followed by the walk-and-turn test (68 percent) and the one-leg-stand test (65 percent).
How accurate are Fsts?
Field Sobriety Test Accuracy 10% or higher. After assessing the data, the institute recommended that the horizontal gaze nystagmus, walk and turn and one-leg stand tests be used to test for impairment.
Does caffeine cause HGN?
Caffeine can also cause the eyes to move more rapidly than usual, which could cause a failed HGN test. While the person might not fail a breathalyzer test, there is an increased risk of failing one of the standard field sobriety tests that are typically administered by law enforcement."
How do you pass the HGN test?
Passes -- Smooth Pursuit. The stimulus should be moved at a speed that takes at least two seconds from the center position to the side position. At a rate of at least four seconds per eye per pass (two second out to the side and two seconds back to center), this phase of the HGN should take at least 16 seconds.
Are field sobriety tests scientifically proven?
The scientific basis for FST's The big problem with Field Sobriety is that their scientific validity has never been verified. The tests were developed by an “interest group”, and the methodology was questionable.
What are the 3 standard field sobriety tests?
During a field sobriety test, there is no pass or fail. Instead, an officer should observe for clues that may indicate alcohol impairment. There are only three validated tests by the NHTSA which are the horizontal gaze nystagmus test, the walk-and-turn test, and the one-leg-stand test.
What are the 3 field sobriety tests?
Field Sobriety Tests refer to standardized tests to initially assess and determine intoxication, namely: the eye test (horizontal gaze nystagmus), the walk-and-turn and the one-leg stand.
What drugs cause horizontal gaze nystagmus?
Only 2 things cause Horizontal Gaze Nystagmus: Refer to NHTSA Student Manual VIII-3 The DIP Drugs (Depressants such as alcohol, xanax, valium, etc.; Inhalants, and PCP), and Serious Brain Stem Injury.
Why do cops have you follow their finger?
Using a Finger for the Horizontal Gaze Nystagmus Test at a DWI Stop. The HGN test measures the steadiness of your eyes while you follow an object with your eyes. Officers often use their finger or perhaps a pen for this test because they can easily see your eyes while providing an object for you to follow.
What are the signs of intoxication to look for when performing the horizontal gaze nystagmus?
HGN Cues/Clues of Intoxication There are a total of three clues that can be assessed in this test: lack of smooth pursuit, distinct nystagmus at maximum deviation, and the onset of nystagmus prior to 45 degrees.
What is Sfst used for?
The Standardized Field Sobriety Testing (SFST) course, also known as the DUI or DWI Detection course, is a comprehensive course that is designed to increase the student's ability to detect impairment in drivers.
What is the legal limit for intoxication in Texas?
0.08 percentWhen am I legally intoxicated? You are legally intoxicated in Texas when your blood alcohol concentration reaches 0.08 percent, but you are breaking the law as soon as drugs or alcohol affect your driving — or flying or boating — ability.
How accurate is the HGN test?
However, officers who conducted an HGN test individuals who were sitting were only able to accurately determine impairment 87.7% of the time.
What agency did the study to see whether a driver was sitting or standing during the HGN mattered to the?
The National Highway Traffic Safety Administration (NHTSA) did a study to see whether a driver was sitting or standing during the HGN mattered to the result. They said:
What does the officer look for in an eye test?
In this test, the officer will use a pen or his finger and track the movement of the eyes. The officer will look for involuntary fluttering of the eye (nystagmus) which, if present, is a possible indicator of impairment.
Can you take an HGN test if you are in an accident?
If someone is in an accident, it might be impossible for an HGN test. In those cases, the test is administered with the suspect sitting or lying down. In the study, participants received an HGN examination standing, sitting, and lying down.
How accurate is the HGN?
In addition, the police are trained that the HGN achieves 77% accurate at detecting subjects at or above a .10% blood alcohol concentration. But that is not the whole story.
What is the horizontal gaze nystagmus test?
The horizontal gaze nystagmus test is an eye test approved by the National Highway Traffic Safety Administration (hereinafter NHTSA) as a tool to detect clues of impairment in drivers. The HGN test is one of three psychomotor tests approved as part of the standardized field sobriety testing protocol employed by law enforcement officers throughout the United States and used here in Ohio.
Is the field sobriety test valid?
The validity of Standardized Field Sobriety Tests results is dependent upon law enforcement practi tioners following the established, standardized procedures for test administration and scoring. NHTSA’s SFST Student Manual states that the procedures demonstrated in the training program describe how SFSTs should be administered under ideal conditions, but that ideal conditions do not always exist in the field. Variations from ideal conditions, and deviations from the standardized procedures, might affect the evidentiary weight that should be given to test results.
Is the horizontal gaze nystagmus test present in marijuana impairment cases?
The horizontal gaze nystagmus test is not present in marijuana impairment cases. In State v. Dixon, 2007-Ohio-5189 (Ohio Ct. App. 12th Dist. Clermont County 2007), the court addressed the issue of standardized field sobriety tests and marijuana impairment. Relying upon the NHTSA standards, the court concluded that observations as to performance on the walk & turn test and the one-leg stand test were indicative of impairment, thus allowing those to be used against a suspected marijuana user. The HGN test, however, is not indicative of marijuana impairment. According to NHTSA nystagmus would not be present due to marijuana and, as such, it was plain error to admit evidence of the horizontal gaze nystagmus test against the defendant accused of marijuana impairment.
What is the NHTSA test?
NHTSA has laid out detailed procedures for officers to follow when administering the horizontal gaze nystagmus test, as well as clues to look for in scoring the test. However, law enforcement officials are notorious for administering the test incorrectly.
What is the purpose of the horizontal nystagmus test?
The Horizontal Nystagmus Test (HGN) is a standardized field sobriety test (FST) that police often administer in order to gauge whether a DUI suspect is under the influence of alcohol. The officer instructs the suspect to follow (with his eyes) a stimulus to the left and to the right.
How to check a suspect's right eye?
Check the suspect’s right eye by moving the object to the suspect’s right. Have the suspect follow the object until the eyes cannot move further to the side. Make this movement in about two seconds, and observe:
Why do police officers administer the test incorrectly?
This generally stems from lack of training, improper training, and failure to adhere to the proper procedures.
Is the horizontal gaze nystagmus test valid?
In California, the horizontal gaze nystagmus test is considered a reliable and valid testing procedure. 14 Hence, HGN test results may be admitted in evidence to corroborate or attack the allegation that a particular defendant had been driving under the influence of alcohol. 15.
What is the HGN test?
The Horizontal Gaze Nystagmus (HGN) Field Sobriety Test checks your eyes for involuntary jerking as you gaze to the side. The test begins by the police officer placing the tested person in the instructional stance where the feet are placed together and the arms are kept to the side. The tested person is told to maintain that position until told otherwise and asked if they understand. Once the tested person is in the in the instructional position the Deputy must qualify the tested individual as a candidate for the test by ensuring that the eyes exhibit equal tracking and have equal pupil size. If the eyes do not track equally or the pupils are of different size the person is not a candidate and the test shall not be conducted. (And those symptoms may have other causes than intoxication).
What is HGN in physics?
What is HGN? The Nystagmus in the Horizontal Gaze Nystagmus (HGN) Field Sobriety Test is derived from the Greek word, νμσταγμνσ, meaning drowsiness, is derived from νμσταζειν, meaning “to nod in one’s sleep”), the rhythmic to-and-fro oscillation of the eyes, (such as you might see in REM sleep), which was regarded as a mystery throughout history.
Why do the police use HGN?
The manual used to train all officers in the United States, the NHTSA manual, contains the instructions and strict testing protocol for this test because it is believed to be strongly correlated with alcohol impairment at or above a .08% blood alcohol level. The HGN instructions from the manual read as follows:
How to detect a stimulus?
You may observe resting nystagmus at this time. Check the suspect’s eyes for the ability to track together. Move the stimulus smoothly across the suspect’s entire field of vision. Check to see if the eyes track the stimulus together or one lags behind the other. If the eyes don’t track together it could indicate a possible medical disorder, injury or blindness. Next check to see that both pupils are equal in size. If they are not, this may indicate a head injury”.
What is the HGN field sobriety test?
Horizontal Gaze Nystagmus (HGN) Field Sobriety Test. One of the standardized field sobriety tests (FSTs) used by law enforcement for a DUI arrest is the Horizontal Gaze Nystagmus (HGN) Field Sobriety test, often abbreviated as the HGN FST.
What happens if your eyes are not tracking?
If the eyes do not track together, or if the pupils are noticeably unequal in size, the chance of medical disorders or injuries causing the nystagmus is present” (P. VIII-5, NHTSA SFST student manual, HS 178 R1/02).
How many clues are there in the eye test?
There are a total of three clues that can be assessed in this test: lack of smooth pursuit, distinct nystagmus at maximum deviation, and the onset of nystagmus prior to 45 degrees. Each eye is scored independently for three clues in each eye giving a total of six indicators/cues.
How accurate is the HGN test?
According to the most recent studies, HGN is the most reliable of the tests to determine if a person’s BAC is at or above a .08%. This test was found to be 88% accurate, which means it is inaccurate 12% of the time.
What is the difference between HGN and Nystagmus?
Nystagmus is the involuntary jerking of the eyes. HGN is the involuntary jerking of the eyes, occurring as the eyes gaze to the side. Because this movement is involuntary, people are usually unaware of the jerking and they are not able to control it or stop it from happening.
How many clues are there in a BAC test?
That is a total of 6 clues. If the test is performed properly and 4 or more clues are noted, it is likely the person’s BAC is at or above .08%. But remember, this is only 88% accurate.
Field Sobriety Test Accuracy
During the late 1970s, the National Highway Traffic Safety Administration (NHTSA) tasked the Southern California Research Institute (SCRI) with evaluating the dozens of field sobriety tests that were in use to determine which were the most accurate.
Challenging Field Sobriety Tests
There are expert witnesses who study the field sobriety tests, and understand their weaknesses. Any person arrested for drunk driving on the basis of a field sobriety test score is encouraged to challenge these tests in an effort to fight their criminal charge.