DUI Detection: field sobriety testing

Published Feb. 2, 2012
By Staff Sgt. Nicole Mickle
Joint Base Charleston Public Affairs

JOINT BASE CHARLESTON, SC -- It is two o'clock in the morning and a car swerves in and out of lanes, barely missing on-coming traffic. The car speeds through a red light at an intersection almost causing an accident with another vehicle. A police officer witnesses the event, pursues the driver and speeds up to initiate a traffic stop.

The officer approaches the driver's vehicle and the driver's window slowly rolls down as the overwhelming smell of alcohol escapes and hits the officer's nose.

"Is there a problem officer?" the driver says in a slurred voice that is almost impossible to understand. After the officer speaks with the driver and gets his information, he asks him to step out of his vehicle. The driver has trouble opening his car door and when he finally does, he staggers out and almost falls as he tries to regain his balance. The officer already has a pretty good idea what he is dealing with.

Most of us can make the assumption that the driver of this vehicle is probably under the influence of alcohol. We all know the signs of someone who is "wasted." The real question is; how does a police officer identify someone who is at or is just above the legal blood alcohol content and is behind the wheel? For some, this can be only two or three drinks.

Joint Base Charleston's 628th Security Forces Squadron members participated in a standardized field sobriety testing course, Jan. 23 to 26 to find out. The four day course is designed to train and certify law enforcement officials to use driving under the influence detection techniques and national standardized.

"This is the first time we have conducted the training here at the air base," said Benjamin McSwain, a 628th SFS law enforcement officer and a certified instructor for the course. "Before, it was only conducted at the weapons station but now that we can offer it at both locations, more SFS members will benefit from receiving this training."

NHTSA created the standardized field sobriety Test in 1981. The test uses three tests in combination: the one-leg-stand, the Horizontal Gaze Nystagmus test and the walk and turn.

The HGN test is considered by many law enforcement officers to be the most effective technique to provide evidence of alcohol in a driver's system. HGN refers to a lateral or horizontal jerking when the eye gazes to the side. Alcohol consumption hinders the ability of the brain to correctly control eye muscles causing nysagmus, the jerk or bounce associated with HGN.

"People vary in their physical and cognitive capabilities and tolerance to alcohol," said McSwain. "Some experienced drinkers perform physical or cognitive tests accurately, even with a BAC greater than 0.10 percent. However, they can't hide the physiological effects of alcohol from an officer who is trained in administering the HGN test because HGN is an involuntary reaction and the individual has no control over it."

While the students administered the HGN test, they were looking for several clues: lack of smooth pursuit, distinct nystagmus where the sclera, or white part of the eye is not visible when the subject is looking towards the edge of their peripheral vision for four seconds, and the onset of nystagmus before the eye has moved 45 degrees.

The students were given time to practice each of the tests on each other and then they administered the tests on volunteer participants who had consumed alcohol.

"I really saw a difference from administering the tests on my classmates to administering the tests on the intoxicated volunteers," said Staff Sgt. Sean Van Ness, a 628th SFS law enforcement officer.

Three volunteers participated in the "lab" and were closely monitored by instructor, Kevin Curry, a 628th SFS law enforcement officer. Each volunteer was required to sign a form that outlined what they could and could not do while participating in the training. Their alcoholic drinks were measured and given at specific times. Meanwhile, their BAC was closely tracked by Curry through the use of a breathalyzer. Once the test subjects blew just above the legal limit of 0.08 percent, they were ready to be administered the three field sobriety tests.

"The volunteers are always really surprised how quickly their BAC reading goes above 0.08 percent," said Curry. "Often it is already there after a couple of drinks."

The intoxicated participants were not released from the drunk lab until their BAC was back to 0.0 percent, which took several hours.

In order to successfully pass the course, each student had to pass a practical exam where they properly administered the three tests to another person as well as a written exam.

"This course will definitely give me more confidence when I run into a possible DUI incident during a traffic stop," said Senior Airman Christopher Bryant, a 628th SFS law enforcement officer. "Now that I have had this training, I will be more successful at keeping drunk drivers off the roads."