HGN Test Officer Qualification Issues in DUI Cases

Attacking a horizontal gaze nystagmus test: the officer’s qualification to conduct the test

The horizontal gaze nystagmus test is an ophthalmologic examination

The horizontal gaze nystagmus test is a test of a person’s eye movements. With one eye closed the individual fixes the other eye upon a pencil-beam of light from a pocket flashlight held by the officer. When the officer moves the beam from left to right and vice-versa, a jerking movement of the eye as it follows the beam of light will occur when the light beam has reached a deviation of 40° or more. Alcohol is said to cause these deviations at lesser angles.

The horizontal gaze test is an opthalmologic examination that requires substantial experience in recognition of the aberration itself (that is, the degree at which the deviation occurs). Many potential eye and neural disorders, and many drugs, can affect the test results.

Four Grounds for Challenging HGN Test Results

The horizontal gaze nystagmus test is often the first field sobriety test administered by the arresting officer. If the police officer claims that you failed the HGN test, your attorney may attempt to raise a reasonable doubt about this result. That reasonable doubt may be based on any of several issues:

• The way the officer administered the test
• The officer's qualifications to conduct the test
• The failure to give the other standardized field sobriety tests along with the HGN test
• The accuracy rate of the horizontal gaze nystagmus test itself

The HGN test is a standardized field sobriety test. This means that the National Highway Traffic Safety Administration (NHTSA) has established that the test must be given in a specific, prescribed manner — or the results are not considered reliable. No deviation from the established protocols is permitted.

Sample cross-examination of arresting DUI officer about the horizontal gaze nystagmus test

The following is a sample cross-examination of an officer about the horizontal gaze nystagmus test used by a Summit defense attorney in a DUI trial in San Jose:

Q: Officer, you have received training in the horizontal gaze nystagmus test, correct?
A: Yes.
Q: The HGN test is really an ophthalmological examination, correct?
A: Yes.
Q: You are not an ophthalmologist, are you, officer?
A: No.
Q: You have had no specified training in ophthalmology, have you, officer?
A: No.
Q: You have not taken any courses in ophthalmology, have you, officer?
A: No.
Q: You hold no degree in ophthalmology, do you, officer?
A: No.
Q: As part of your training in HGN, were you informed that there are many potential eye disorders that can affect the test results?
A: Yes.
Q: You are not qualified to determine whether Mr. Jones had, or has, any eye disorders, are you?
A: No.
Q: In fact you do not know whether he had or has any eye disorders, do you?
A: No.
Q: Yet eye disorders would affect the HGN result, correct?
A: I believe so.
Q: Were you also taught in your course in HGN that neural disorders can also affect the HGN test result?
A: Yes.
Q: You have no special training in detection of neural disorders, do you officer?
A: No.
Q: You did not perform any tests to determine whether Jones suffered from any neural disorders, did you?
A: No.
Q: You did not consult any medical records of Mr. Jones to determine whether he had any neural disorders, did you?
A: No.
Q: You did not ask Mr. Jones whether he suffered from any neural disorders, did you?
A: No.
Q: Officer, you were also informed that many prescription drugs can affect the HGN test results, correct?
A: Yes.
Q: When you stopped Mr. Jones and placed him under arrest, you conducted a physical inventory of his personal property, did you not?
A: Yes.
Q: In that physical inventory, one of the things that you found was blood pressure medication, correct?
A: Yes.
Q: You verified that prescription, did you not?
A: Yes.
Q: Mr. Jones properly had a prescription for blood pressure medication, correct?
A: Yes.
Q: The blood pressure medication can affect nystagmus, correct?
A: I do not know.
Q: Did you consult any sources at the time you administered the HGN test to determine whether in fact the blood pressure medication taken by Mr. Jones might affect the test result?
A: No.
Q: You assumed it would not, correct?
A: Yes, I assumed it would not.
Q: Yet in your course you were told that certain prescription drugs can affect the test results, correct?
A: Yes.
Q: And you don’t recall what specific prescription drugs can affect the test results?
A: Not specifically, no.
Q: In fact, you don’t recall how prescription drugs may affect the test results, do you?
A: No.

The Accuracy Rate of the Horizontal Gaze Nystagmus Test

Although the HGN test is considered the most accurate of the various field sobriety tests, it is not a reliable measure of intoxication. Studies indicate that even when the test is administered correctly and in full compliance with NHTSA protocols, its reliability rate is only 77%.

This means that in 23 out of every 100 tests conducted perfectly, the result will incorrectly classify the subject — either falsely identifying a sober person as drunk, or failing to identify an impaired driver. Your attorney can use this statistic to create a powerful reasonable doubt, particularly when the test was also not administered according to proper procedures.

This line of questioning has demonstrated that there are many other causes of nystagmus other than alcohol intoxication, and that the officer is not an expert in the science behind the test.

Attacking the Failure to Administer All Three Standardized Tests

The NHTSA's own research — published in the Department of Transportation report entitled "Improved Sobriety Testing" — establishes that the HGN test is not meant to be used alone. The report states that the combination of all three standardized tests (nystagmus, walk-and-turn, and one-leg stand) gives officers "firm data on which to base an arrest decision." When an officer arrests a driver based solely on the HGN test without administering the other two, your attorney can use the government's own standards to challenge the validity of that arrest.

Sample Cross-Examination: Failure to Give Other Tests and the 77% Accuracy Rate

The following is a sample cross-examination of an officer on these issues:

Q: Officer, are you familiar with a report by the Department of Transportation entitled "Improved Sobriety Testing"?
A: May I see it, counselor?

Q: Please review the report and let me know whether you have seen it before.
A: Yes, I have seen this before; it was part of my training materials.

Q: That report contains an overview of the horizontal gaze nystagmus test as well as a test known as the walk-and-turn test and the one-leg stand test, correct?
A: Yes.

Q: In this case you only administered the horizontal gaze nystagmus test to Mr. Jones, correct?
A: Correct.

Q: You did not administer the walk-and-turn test, did you?
A: No.

Q: You did not administer the one-leg stand test, did you?
A: No.

Q: I would now like to read from the report which you have acknowledged you used in your training on HGN and ask if you agree with this statement: "All drivers whose behavior suggests impairment should be given at minimum, the gaze nystagmus test. The combination of all three tests (nystagmus, walk-and-turn and one-leg stand) . . . will give you firm data on which to base your arrest decision." Do you agree with that statement?
A: Yes.

Q: You did not perform this combination of the three tests, did you?
A: No.

Q: Yet you arrested Mr. Jones after you administered the horizontal gaze nystagmus test, correct?
A: Yes.

Q: The report goes on to indicate the appropriate testing procedures, does it not?
A: Yes.

Q: Did you follow this testing procedure as outlined in the report when you administered the HGN test to Mr. Jones?
A: Basically, yes.

Q: Now you say "basically" you did. Did you, for example, score the subject on the point system used in the report?
A: I did not use that specific system, no.

Q: Officer, did you give the instructions to Mr. Jones as outlined in this report?
A: I do not recall if I gave those specific instructions.

Q: Do you agree, officer, that if the horizontal gaze nystagmus test is not performed properly as indicated in this report, the results are suspect?
A: I agree that the test should be conducted properly. I believe that I did conduct it properly.

Q: You do agree, however, that you deviated from the instructions set forth in this report, correct?
A: Yes, somewhat.

Q: Do you also agree, officer, that even if the HGN test is conducted properly according to this report it will only correctly classify about 77% of suspects as to whether they are drunk or sober?
A: I believe that's correct.

Q: So in 23% of the cases it will not correctly classify suspects, correct?
A: Correct.

Q: That means if there were one hundred people tested and the tests were performed exactly as set forth in this report, twenty-three of those one hundred people would be incorrectly classified as being either drunk or sober using the HGN test, correct?
A: I believe that's correct.

Q: So 23%, or twenty-three people out of one hundred, would be improperly classified even if the test were performed exactly as set forth in this report, correct?
A: That's correct.

This line of questioning has demonstrated that the officer did not conduct the confirmatory tests that would have given him "firm data" for an arrest, and that even under ideal circumstances and properly conducted tests, the HGN test is only accurate 77% of the time.

About The Author

Rabin Nabizadeh

Attorney at Law

Rabin Nabizadeh is a dedicated criminal defense attorney with extensive experience in both Federal and State courts around the Bay Area. He has successfully represented clients in cases ranging from Misdemeanor DUI and Theft to serious felonies such as Grand Theft, Burglary, Sex Crimes, and Murder. Notably, Mr. Nabizadeh possesses a unique understanding of Immigration Law, allowing him to adeptly navigate cases with both criminal and immigration consequences. Fluent in Hebrew and Farsi, he also enjoys playing classical guitar in his spare time.