Field Sobriety Tests reliable?

Anyone who has ever watched a police based reality type tv show has seen a person accused of driving under the influence be required to perform a battery of tests. But what do these tests mean? i.e. what are they measuring? In my years as a police officer and as a criminal defense attorney I have witnesses officers conduct various types of theses so called sobriety tests. Tests that I have witnessed and have myself administered have included:

• The alphabet test - Requiring the accused to start on a particular letter and continue to another identified letter.

• The finger to nose - Requiring the accused to stand in one spot and touch the tip of the nose.

• Watching the pen - Correct terminology for this test is the 'Horizontal gaze nstagmus' Requires the accused to follow an object with the eyes.

• One leg stand - Requires the accused to stand on one leg for 30 seconds. 

• 9 step test - Requires the accused to walk 9 steps on a straight line.

• Coin pickup - Requires the accused to pick up several coins dropped on the floor.  

The list can go on and on. 

In the 1970's the National Highway Traffic Safety Administration conducted controlled studies to determined what tests were actually true measures of a persons sobriety. The results shocked the law enforcement community. Only three tests were determined to correlate with a persons intoxication.

Those tests are:

1. The Horizontal gaze nystagmus test
2. The one leg stand test
3. The nine step walk and turn test

What this means is that the other tests do not have a bearing on a persons sobriety. In other words, a completely sober person could fail the alphabet test, the finger to nose test, etc. Another shocking revelation of the NHSTA study that even with the three tests that correlate with intoxication, if the officer didn't instruct or administer the tests properly then all reliability of the test is gone. 

Even these three tests are not 100% reliable. The one leg stand test and the nine step test are less than 70% reliable. (Meaning that 30% of the time a completely sober person would fail these two tests). The Horizontal gaze nystagmus test is the most reliable test of intoxication but in Tennessee that test is generally inadmissible against the accused.

In a study conducted by Clemson University in 1994 a group of 21 completely sober individuals were instructed to perform field sobriety tests. Fourteen trained officers watched videos of these field sobriety tests and gave their opinion as to intoxication based on the persons performance on the video. (the officers were not told that the subjects were completely sober).  46% of the officers responded that persons they viewed were under the influence of an intoxicant. 

So, knowing that a completely sober person can ultimately fail these so called sobriety tests we must ask the question - can a citizen refuse to perform these tests when asked by law enforcement? The short answer in Tennessee is  - yes. There is currently no law of failing to do the tests. HOWEVER, this does not mean that the officer cannot arrest you for DUI. In fact, your failure to conduct these tests can be used against you in court as "consciousness of guilt".  I personally feel that the ability of the prosecution to use a refusal to take so called sobriety tests  as "consciousness of guilt" is a terrible tragedy.  I hope that the Tennessee Courts will soon overturn previous rulings allowing this practice.