If you’re pulled over for drunk driving, you might have to do field sobriety tests. We’ve all seen them in videos – walk this line, stand here, say the alphabet. But did you know that there’s no credibility behind many of the field sobriety tests that law enforcement officers impose on law-abiding motorists every day?
In 1970, researchers at the National Highway Traffic Safety Administration set out to test the validity of field sobriety tests. They wanted to know if the tests law enforcement officers put drivers through by the side of the road actually found drunk drivers.
What emerged from their studies was a shocking statistic: officers were only able to predict intoxication 47% of the time. That’s not exactly a passing grade.
Researchers found that the counting or reciting tests are not an accurate predictor of intoxication. Saying the alphabet? Useless. Some officers ask drivers if Mickey Mouse is a dog or a cat. (Turns out there are, in fact, stupid questions.) Reciting tests and trick questions like these prompted officers to incorrectly identify suspects as too intoxicated to drive a shocking 15 percent of the time.
Through their studies, researchers were able to identify three sobriety tests that, when used correctly, are an accurate predictor of intoxication 82 percent of the time. These are the horizontal gaze nystagnus (HGN), the walk and turn, and the one-leg stand. These three tests have become known as the standardized field sobriety tests.
In the horizontal gaze nystagnus test, the officer has the subject watch a pen or other object, so that the officer can then watch involuntary movements of the eye. A suspect that is intoxicated will have a great deal of twitching in the corner of the eye, and their eyes will not shift focus without jerking. There are many demonstrations of this test on the web.
For the walk and turn test, the subject takes a set number of steps on an imaginary line, turns and walks back. In this test, the officer is looking to make sure that the subject does not start until the officers finishes with instructions. The officer also checks to see that the suspect takes only the instructed number of steps and does not use his or her arms for balance when walking. Of course, falling off the line is a sign of intoxication, too.
Finally, the one-leg stand test is similar to the walk and turn test. The officer checks to see whether the suspect uses their arms for balance, and whether the suspect puts his or her leg down sooner than instructed.
Field sobriety tests are not pass/fail. Rather they are indicators that the investigating officer uses to decide whether to give the suspect a Preliminary Breathalyzer Test (PBT).
Despite the scientific validity of the standardized field sobriety tests, many law enforcement officers still refuse to use them and only them. In other words, many local law enforcement officers trust their own methods more than they trust the research of the National Highway Traffic Safety Administration. That’s concerning.
Back in my assistant prosecutor days, I heard all kinds of excuses from law enforcement officers as to why they wouldn’t stick to the standardized field sobriety tests. “I use the tests I’ve always used,” one complained. My favorite excuse was that “The people who would be on a jury in this county aren’t going to understand that pseudo-science.” These officers open the door for a knowledgeable defense attorney to argue to a jury that the investigation was flawed.
And of course, a test is only as good as the one performing it. The NHTSA study showed that officers perform the HGN test incorrectly as much as 95 percent of the time. Yikes!
If you are charged with drunk driving, known as Operating While Intoxicated, contact us. We can review your police report and help you determine if the officer performed standardized field sobriety tests in the appropriate manner. If they did not, your case could be dismissed.
You can read about field sobriety tests here.