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The Three Commonly Accepted Field Sobriety Tests


When you are pulled over or stopped at a sobriety checkpoint on suspicion of driving under the influence, the smell of alcohol is often not enough to warrant establishment of probable cause, which is mandatory in order to legally make an arrest. Instead, officers will usually turn to other tools that are specifically designed for the job: field sobriety tests. A field sobriety test is a task designed to show intoxication levels based on passing or failing to complete it.

In the past, field sobriety tests used to be pretty much a gut-feeling type of deal, where officers could have people do just about anything and then claim in court that their failure to do so meant they were drunk. However, the process today is much more refined. Careful study and testing has led to the standardization of three widely-accepted field sobriety tests which officers almost exclusively utilize when investigating people today.

On this blog, we’ll briefly describe each of these tests so you can determine if yours was conducted correctly, or if you may have in fact been falsely arrested.

Walk & Turn

The walk-and-turn test involves the subject walking in a heel-to-toe fashion (sort of like they’re on a balance beam) in a straight line for a certain number of steps. One they reach that number, they are required to pivot without lifting their feet and walk back the exact same number. While doing this, officers usually instruct the subject to complete a mental task as well, such as counting to 30 or reciting the alphabet. This divides the subject’s attention, and divided attention makes nearly anything impossible to do while intoxicated.

One-Leg Stand

The one-leg stand test is also a divided-attention test, requiring subjects to split their mental capacity between a physical test and a mental one simultaneously. The subject is required to stand on one foot with their other leg lifted and toes pointed outward. While standing in this position, officers then instruct the subject to complete a mental task, often counting to 30 by “one thousands.”

Horizontal Gaze Nystagmus

The horizontal gaze nystagmus test is perhaps the most commonly-used test in modern law enforcement because it’s extremely easy to conduct and very difficult to confuse. It’s also the most accurate of the three accepted tests. All the officer has to do is hold a finger, pencil, or small light up slightly above the subject’s eye level and then instruct them to follow the object without moving their head as they move it slowly back and forth from side to side.

In this test, officers are looking for an involuntary twitching motion in the eyes, which is caused by intoxication causing the brain to lose the ability to control these muscles as precisely as it normally can. While this isn’t perfectly accurate (those with attention disorders, hyperactivity, or extreme fatigue have also been found to fail it quite frequently), it’s generally considered a good starting point.

Flaws with Field Sobriety Tests

Do these tests sound difficult? They are. A little under half of all people who take these tests completely sober either fail them or are barely able to pass. Standing on one foot for an extended period of time can be exhausting, and many people simply can’t do it to begin with, as it’s a task that requires a pretty high level of coordination and dexterity. Add in the nerves and pressure of having to take this test on the side of the road with prying eyes watching and the threat of being arrested if you fail and loads of people simply can’t complete the tests accurately.

That doesn’t mean they’re guilty of driving under the influence, and it also doesn’t mean you should be complacent if you are arrested.

Call the Law Offices of Joseph R. Donahue, LLC at (201) 574-7919 to request a case evaluation if you’ve been charged with driving under the influence in New Jersey.

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