(401) 862-9520
Rhode Island Attorney

The (Un)Reliability of Field Sobriety Tests

The (Un)Reliability Field Sobriety Tests

The first and most important fact to know about Field Sobriety Tests is that they are VOLUNTARY!!!!!

A Rhode Island driver is not under any legal, moral, ethical or other obligation to perform these tests at the officer’s “request.”  Of course, most drivers do not know that; they assume that because the officer “requests” them to do these tests that they must be performed.


Almost any good DUI attorney will advise you to never take the Field Sobriety Tests.  EVER!

The Field Sobriety Tests are fraught with problems.

If they are not administered and scored exactly as required by the National Highway Traffic Safety Administration, they have no reliability.  Frankly, most officers fail to follow the strict mandates required by the National Highway Traffic Safety Administration when they conduct these tests.  They either administer Field Sobriety Tests wrong, or conduct them in a manner (or on a driver) not approved by the National Highway Traffic Safety Administration, or grade the evaluations improperly, or ALL OF THE ABOVE.

According to the National Highway Traffic Safety Administration, when administered or scored incorrectly, the officer’s evaluations have ZERO reliability.

But it gets even worse.  The National Highway Traffic Safety Administration admits that even under optimal weather conditions, and even when the officers do everything right, sober drivers “fail” the Field Sobriety Tests at an alarming rate.  Specifically, 32% of sober drivers fail the Walk and Turn test.  35% of sober drivers fail the One Leg Stand test.  And finally, 23% of sober drivers fail the Horizontal Gaze Nystagmus test.

In addition to the foregoing, research study after research study has shown that Field Sobriety Tests are designed for failure.  Consider the following:

In 1977, the original National Highway Traffic Safety Administration study concluded that 47% (almost half) of all drivers who “failed” the tests had had a blood alcohol concentration of less than .10, the legal limit at the time the tests were developed.

Let’s face it, that result is hardly much better than flipping a coin, and as you will see, this study was probably the most accurate of all subsequent studies, as confirmed by Dr. Cole of Clemson University in 1991.

In 1981, the same researchers who developed the Field Sobriety Tests conducted another study to improve the error rate.  This self serving study had poor reliability coefficients far below standards accepted by the scientific community.  Additionally, In a transparent effort to improve the credibility of the Field Sobriety Tests, the “researchers” eliminated test subjects with blood alcohol concentrations between .09 and .11 percent, and selected only those test subjects with excessively high readings of .15 or higher or excessively low readings of below .05.

Even when the deck was stacked, the study concluded that Field Sobriety Tests still had a false positive failure rate of 32%.  This means that nearly 1/3rd all drivers who “failed” the tests had a blood alcohol concentration below the legal limit.

In 1986, another group of researchers tested the reliability of Field Sobriety Tests.  This study concluded that even when the tests are administered honestly and accurately, and under ideal weather conditions by experienced and trained officers, the Field Sobriety Tests still identified nearly 1/4th of all innocent DUI suspects as guilty.

In 1987, many of the original researchers from 1977 conducted yet another study.  This time the researchers conceded that while Field Sobriety Tests may indicate the presence of alcohol, they do not accurately measure driving impairment!

The researchers finally admitted that these tests do nothing more than determine balance, steadiness, and reaction.

They concluded that there was no apparent connection between these variables and driving ability since neither a steady stance nor simple movement time is essential to the safe operation of a motor vehicle.

In 1991, Dr. Spurgeon Cole of Clemson University conducted a study on the accuracy of Field Sobriety Tests.  His staff videotaped twenty one (21) individuals performing Field Sobriety Tests, then showed the tapes to fourteen (14) police officers and asked them to decide who had “had too much to drink to drive.”  Unknown to the officers, the blood alcohol concentration level of each of the twenty one (21) subjects was .00.

Despite the ideal laboratory conditions and the .00 blood alcohol concentration level, 46% of the officers gave their “opinion” that the subject was too drunk to drive.  This means that the Field Sobriety Tests were slightly more accurate at predicting intoxication than flipping a coin.