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The subjective nature of field sobriety testing

On Behalf of | Sep 17, 2021 | DUI/DWI/Drunk Driving

When police officers suspect someone driving under the influence, they pull them over and conduct a battery of testing to see if their suspicions have any merit. Not all tests have the same level of effectiveness.

Looking into the eyes of a suspect

In addition to the one-leg stand and walk-and-turn tests is Horizontal Gaze Nystagmus. It is the technical term for an officer to place a small object 12 to 15 inches from a suspect’s nose and then move it from side to side. Nystagmus is defined as the involuntary jerking of the eyeballs. Before starting the test, the officer must conduct an evaluation of the eyes to ensure that both pupils are of equal size and both eyes can visually follow an object in front of them.

Specific signs coming from both eyes can possibly determine alleged intoxication and include:

  • Eyes jerking or bouncing
  • Signs of nystagmus before the eyes reach a 45-degree angle
  • Maximum deviation of the eyes jerking within four seconds while looking to the side

Four or more clues can result in probable cause for a DUI arrest. However, that does not mean a suspect will be found guilty. Field sobriety testing is subjective at best. According to the National Highway Safety Administration (NHTSA), less than half were accurate. Following the establishment of more testing standards and the accuracy rate reportedly jumped to 82 percent.

Yet, mistakes can still be made by officers that could be contested in court. Medical conditions can also play a role in a suspect failing a field sobriety test. Law enforcement officers are not doctors and lack medical training that could result in a judge ruling that the results are inaccurate, if not throwing out the entire case.

Drunk driving convictions carry multiple consequences, from losing a driver’s license to incarceration. The help of a skilled defense attorney can make a significant difference in the outcome of a criminal case.