Eye Tests and DWI Charges: Can the Test Be Trusted?


Upon pulling over a driver on suspicion of driving while intoxicated (DWI), many Texas police officers will ask the driver to perform one or more “field sobriety tests.” One common test is known as the “horizontal gaze nystagmus” or “HGN” test. It asks the driver to follow a moving object with his or her eyes. The action of the eyes as they follow the object is supposed to tell the police officer something about the driver’s state of drunkenness – but does it really?

DWI testing

Many studies have found the HGN test may not be as reliable as many officers believe. One of the main reasons this so-called “sobriety test” should be questioned in every DWI case is that nystagmus, or eye movement, can be caused by many things – not just alcohol.

Just a few of the medical conditions that can cause nystagmus even when a person is completely sober include:

  • brain damage, such as a traumatic brain injury,
  • brain tumors or other diseases involving the tissues of the brain,
  • epilepsy and other neurological disorders,
  • problems with the inner ear, including vertigo
  • naturally-occurring nystagmus.

At Peek Law Group, L.L.P. our experienced Austin, Texas criminal defense attorneys can help you fight a DWI charge. We’ll strive to protect your legal rights to the fullest possible extent while also working to secure the best possible outcome in your case. For a free and confidential case evaluation, call us today at  (512) 399-2311.

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