I have been representing people charged with DUI in Ohio since 1994 on a daily basis. In nearly 95% of my cases, I've had to deal with evidence of field sobriety tests. These roadside exercises are hard for anyone to do, let alone when a person is scared. So, what is the science behind the standard battery of field sobriety tests (standing on one leg, the walk and turn, and the pen in front of the eye test (HGN))?
In a nutshell, these exercises were developed by two researchers in the late 1970's - Dr. Marcelline Burns and Dr. Herb Moskowitz. Both researchers were with the brand new institute called the Southern California Research Institute. Dr. Moskowitz had been doing research on rats and the effects of alcohol and other drugs. When the federal government issued a Request for Proposals in 1975 to come up with some roadside DUI tests, SCRI won the contract. From what I can tell, it is one of the very first research projects Marcelline Burns did. In fact, on her CV, I have not seen any other published projects before 1975.
Dr. Burns first report to the federal government was issued in 1977 (Psychophysical Tests for DWI Arrest, U.S. Dept. of Transportation, National Highway Traffic Administration, DOT-HS-5-01242). 238 volunteers and 10 police officers from Los Angeles county participated in this lengthy study. All 238 volunteers were tested in a laboratory setting, not roadside. Nor were any of the volunteers under the threat of arrest. The published false arrest rate from the 1977 study was an alarming 47%! That means that 101 of the 238 people "arrested" for DUI, 47 had a blood alcohol level below the legal limit.
In 1981, Dr. Burns submitted another study on field sobriety tests to the federal government. (Development and Field Test of Psychophysical Tests for DWI Arrest, U.S. Dept. of Transportation, National Highway Traffic Administration, DOT-HS-8-01970). This time, in order to lower the error rate, 78% of the subjects were dosed with alcohol at either a very high level (.150% or greater) or doses at a very small level (.050% or below). In other words, nearly 80% of the subjects were what we call "gimmes".
The error rate dropped from 47% to 32%. That means that of the 118 people "arrested" for DUI, 37 of them were improperly accused of DUI. More startlingly, of the 37 people falsely accused of DUI, 18 subjects had absolutely no alcohol in their system!
So, if you or someone you know was arrested for DUI primarily on the basis of "failing" field sobriety tests, it is highly recommended that you consult with a lawyer with a deep understanding of the alleged science behind these roadside exercises.