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DWI Eye Test: Unrelated to Driving Ability

The DWI Eye Test is very misleading. The reliance of the DWI Eye Test is now past a “common misconception” and has now become a major lie. Many officers and prosecutors claim that HGN is the “best DWI test” for finding out if a person is DWI. They claim that anyone who has HGN is unsafe to drive and try to put the test on a pedestal. However, the DWI Eye Test has absolutely nothing to do with a person’s ability to drive safely. Even in the many (flawed) verification studies, the primary purpose of the eye test is to detect the possibility that a person is at or above a certain BAC. In some ways, the test does seek to indicate “impairment,” but the test does very little to test physical impairment.

DWI Eye Test Validation Problems

At the base level, the DWI Eye Test is problematic due to the many flaws in both verification and actual practice. To start, the verification studies for the eye test mostly occurred in laboratory, rather than practice, settings. This means that they had access to equipment such as protractors, chin rests, and whatnot. Even the the “field testing” studies, there were problems such as the presence of PBT devices (portable breathalyzers) that may have influenced the interpretation of the test. Some field studies also lacked oversight, meaning that the police agencies involved sent data to the study, but the actual administration of the test was not personally observed to determine accuracy. Further, there are over 40 different types of nystagmus, but officers do not receive sufficient training to differentiate between all of them.

Another main concern with the validation studies has two parts. First, the laboratory portion of the studies excluded certain subjects (e.g., elderly), occurred during the day, and subjects did not have reason to fear arrest. Second, the field studies had bias in favor of the study because most subjects already belonged a “high risk” group (e.g., stopped at night in areas with many bars). Finally, most studies did not account for field factors that interfere with the test (e.g., anxiety, fear, age, etc.).

The DWI Eye Test and Driving Ability

There are ZERO studies validating the eye test for testing physical tasks such as driving ability. There is also very little research on the eye test’s ability to determine mental impairment. Part of this is due to the instructions for the test. Without going into the exact science of eye movement, it should be common sense that people do not drive without moving their heads. Yet, the eye tests requires subjects to move “eyes and eyes only” during the tests. Officers tend to consider any head movement as a sign of intoxication. Regardless, officers receive very little training (about 3 hours of a 3-day course) on the eye test. This often leads to incorrect performance of the test. Even then, officers rarely test “sober” people so may not know the appearance of natural, non-impaired eye movement.


More about Mimi Coffey & The Coffey Firm

When people look for a Top DWI Attorney or Best DWI Attorney, they look for experience, certification, and respect in the legal community. Mimi Coffey is a nationally-renowned trial attorney, board-certified in DWI by the NCDD. She has been practicing for over 24 years and is an author of multiple DWI Defense textbooks. She is also a national and state-wide lecturer on the law.

The Coffey Firm handles a wide variety of cases, including Unlawful Carrying Weapon (UCW), Assault (including family violence), and Possession charges. We can also help you try to get a DWI off your record or avoid probation revocation. The Coffey Firm offers fair DWI payment plans and free consultations.

Mimi is also listed on several “top criminal lawyer near me” directory listings such as Wise County DWI Lawyers, Tarrant County DWI LawyerDallas County DWI attorney, Collin County DWI attorneys and Parker County DWI attorneys. Mimi is a caring DWI Lawyer in Dallas – Fort Worth. She is also involved in the Texas Tech School of Law foundation and enjoys using the skills she has developed to give back to the community.