Field Sobriety Tests: The Reasons Why They Might Be Unreliable

Law Articles

Field sobriety tests are the subject of hot debate. On one hand, a motorist that's clearly over the legal alcohol limit will usually display characteristic behavior that makes them easy to spot. On the other hand, many of the field tests require skills that could be compromised for reasons other than inebriation. In fact, in a U.S. Department of Transportation study, no field sobriety test was 100% accurate. This makes it difficult to say whether these tests are useful or a detriment to motorist's basic rights.

To better understand this debate, it's useful to look at each individual type of field sobriety test. Each one has specific strengths as well as situations where it isn't necessarily the most appropriate measure.

Horizontal Gaze Nystagmus

Nystagmus is the medical term for involuntary jerking of the eyeball when it is disturbed. In this field sobriety test, the officer will ask you to move your gaze to the side while tracking a pen or other object. They will often pair this with a flashlight to aid in their ability to accurately observe your eyes. The signs of impairment that they're looking for include:

  • Inability to smoothly track the object
  • Eyeball twitching at the extreme angles
  • Earlier twitching as your gaze progresses to the extremes

Inaccuracies in this test come from two major sources. The first is the environment. Wind, light, and other variables can cause involuntary reactions from your eyes in a field test environment. These can often be misinterpreted as a sign of impairment, even with experienced officers. Also, since most field tests happen at night, headlights and other flashes make this scenario even more likely.

The second source of inaccuracy comes from the medical history of the motorist. There are a number of medical reasons for nystagmus, including nearsightedness, epilepsy medications, and inner-ear inflammation. The attending officer might not know of these conditions--in fact, the motorist themselves might not know if they have an inner-ear infection. For these reasons, it's perfectly conceivable that sober motorists could fail the horizontal gaze nystagmus test.

Walk and Turn

Walk and turn tests consist of asking the motorist to take a number of heel-to-toe steps, before turning around 180 degrees and walking back in the exact same fashion. This test is determined to be simple for a sober adult, and the instructions follow a pre-set script. All of this protocol is designed to ensure that the motorist is perfectly aware of the instructions and capable of following them.

However, the action of walking heel-to-toe is unnatural for many people--particularly those with out-toed gaits. There are a number of legitimate physical reasons why a person's natural stride involves their big toe pointing away from their center line. For these individuals, a heel-to-toe step is actually quite difficult--worse so when combined with the nerves and anxiety of a traffic stop. 

One-Legged Stand

This classic sobriety indicator involves the motorist standing on one leg for thirty seconds. Any wobble or excessive use of arms to balance could indicate a significant impairment. Of all the tests used to screen for inebriation, this one is arguably the most unfair.

Even athletes have issues with this position, and focus on it in their training for maximum performance. On top of that, the inability to perform this pose has been linked to damaged blood vessels in the brain--indicating a higher risk of having a stroke. Regardless, unless you practice this position regularly, it's likely that you'll fall out of a one-footed stance, even if you haven't had too much to drink.

Basically, field sobriety tests can be effective to spot inebriated motorists, but they can also flag innocent people. If you have questions about that way that your test was handled, your best bet is to solicit professional legal advice. They'll be able to look at your unique circumstance and help determine whether your rights were violated or not. Visit for more information. 


28 July 2015

Car Accident Clues

It can be hard to know what to do to protect yourself legally in the immediate aftermath of a car accident. You’re liable to be disoriented or in shock, you may be injured, and you’re surely worried about your passenger or the other driver. At least, that’s how I felt. The thing is, the things you say and do in the immediate aftermath of an accident may affect a legal case later. Depending on who’s at fault and what the laws are in your state, you may want to sue the other driver for damages, or you may find yourself being sued. My blog is designed to give you tips for a car accident lawsuit, no matter which side you find yourself on.