How accurate are field sobriety tests?

On Behalf of | Aug 3, 2018 | Field Sobriety Tests

We’ve all seen the following scene play out on TV: On the side of the road a car is parked, the headlights lights still left on. The driver is out of the vehicle, standing on the shoulder of the road, while an officer instructs them to stand on one foot or touch their finger to their nose. The driver starts to sway, or even completely loses their balance.

Is this really how it goes?

While not all that you see on the screen is real, there are some aspects to field sobriety testing that are in fact very accurate. In the above scenario, not only is standing on one foot a very common testing method to try and determine if someone is under the influence, it’s even one of the tests the National Highway Traffic and Safety Administration endorses.

What are the three common field sobriety tests?

There are three field sobriety tests the NHTSA endorses:

  • One-leg stand: This sounds like what it is. An officer has the driver stand on one foot – for about 30 seconds or so – to see if the driver sways, loses balance or needs to put a foot down for balance. While this can help determine if someone is under the influence, this type of test is also extremely difficult for many sober people to do. There are plenty of drivers who “fail” this test, even though they are either sober or well below the legal limit.
  • Horizontal gaze nystagmus: The HGN test is when an officer has a driver follow the tip of a pen – or something similar – with their eyes, without turning their head. This is not to test whether you can see the object. It is to give the officer a chance to see how your eyes react. It’s normal for some jerking of the eyes to occur, but if it’s exaggerated, this may be a sign of impairment. However, this is also not always accurate, as medical or mental health problems can significantly impact how someone’s eyes react. This means, like with the one-legged stand, sober people or those under the legal limit may appear to be more intoxicated than they truly are.
  • Walk and turn test: During this test, an officer will order a driver to take approximately nine steps in one direct – placing their heel to their toe – in a straight line, before turning one foot and walking back. Like the other tests mentioned, this can show if someone is impaired, but can easily be “failed” by someone with balance, coordination cognitive issues.

Can you challenge field sobriety test results?

Yes. You can challenge the findings of a field sobriety test. These tests are not the final say and can be inaccurate. For example, if someone is already tired, their balance is going to be off. Certain medical conditions and medications can also greatly impact how well someone is going to perform field sobriety tests. Outside conditions – rain, wind, poor lighting – to name only a few, are also all contributing factors to how well someone does.

Do not think that just because you “failed” the field sobriety tests that the case is open and shut. You can absolutely challenge the findings of field sobriety tests.

Watch how we can help you with your legal situation


Do You Have a Defense?

Do You Have a Defense?

Avvo Clients' Choice 2018 Criminal Defense    Avvo Clients' Choice 2018 Criminal Defense

Charles Waechter | Premium
FindLaw Network