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Challenging the accuracy of a horizontal gaze nystagmus


Napa-County-Creek-DUI-lawyer3-300x225According to a Napa County Creek DUI lawyer, one of the first field sobriety tests a police office may administer is the horizontal gaze nystagmus, or HGN, test. This test may be unreliable for several reasons.In the event that the police officer says that you failed the HGN test, your Napa County Creek DUI lawyer might challenge the results in court in order to create reasonable doubt regarding the test result. There are several factors about which reasonable doubt could be raised including:In the event that the police officer says that you failed the HGN test, your Napa County Creek DUI lawyer might challenge the results in court in order to create reasonable doubt regarding the test result. There are several factors about which reasonable doubt could be raised including:

  • The rate of accuracy for the HGN test.
  • An officer’s failure to administer additional tests along with the HGN test.
  • The officer’s training and certification to administer the HGN test.
  • The method used to administer the HGN test.

The reliability rate of the HGN test

Some experts consider the HGN test to be the most accurate of the field sobriety tests used by law enforcement officers. However, the test is not completely accurate. According to studies on the test, the reliability rate is just 77%, even when it is correctly administered.

Federal requirements for the HGN test

The National Highway Traffic Safety Administration – or NHTSA – has stipulated that HGN tests have to be administered in a specific way, or they will not be considered reliable. In other words, the HGN test is a standardized field sobriety test.

A Napa County DUI attorney provides an example of cross-examination of police officer regarding the HGN test

In order to challenge the HGN test in court, an attorney may cross-examine the arresting officer regarding the administration of the test.

Q: Have you ever seen or are you aware of the Department of Transportation report named, “Improved Sobriety Testing?”
A: Can I see the report?

Q: Please look over the report and tell me whether or not you have seen it.
A: This report was included with my other training materials, so I have seen it before.

Q: Is it true that this report contains a description of several sobriety tests, including the one-leg stand test, the walk-and-turn test and the HGN test?
A: Yes.

Q: in this case, you administered only the HGN test. Is this correct?
A: Yes.

Q: You did not ask the defendant to perform the one-leg stand test. Is this correct?
A: Yes.

Q: You did not ask the defendant to perform the walk-and-turn test. Is this correct?
A: Yes.

A Napa County Creek DUI lawyer can review your drunk driving case with you and answer your questions.

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To speak with Blackie Burak, please call 1.866.BLCKDUI or (925) 933-4500 to schedule an appointment.

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Professional & trustworthy DUI & Criminal Defense Lawyer Blackie Burak, Esq. defending your rights.