Field Sobriety Tests

DUI FIELD SOBRIETY TEST:
NHTSA STANDARDIZED FIELD SOBRIETY TEST

When the police or highway patrol suspect that you might be intoxicated, they will make you take a field sobriety test. According to the National Highway Traffic Safety Administration, the NHTSA,”The Standardized Field Sobriety Test (SFST) is a battery of three tests administered and evaluated in a standardized manner to obtain validated indicators of impairment and establish probable cause for arrest.” The three standardized thests are:

Horizontal Gaze Nystagmus (HGN) :

“An alcohol-impaired person will also often have difficulty smoothly tracking a moving object. In the HGN test, the officer observes the eyes of a suspect as the suspect follows a slowly moving object such as a pen or small flashlight, horizontally with his or her eyes. The examiner looks for three indicators of impairment in each eye: if the eye cannot follow a moving object smoothly, if jerking is distinct when the eye is at maximum deviation, and if the angle of onset of jerking is within 45 degrees of center. If, between the two eyes, four or more clues appear, the suspect likely has a BAC of 0.08 or greater. NHTSA research found that this test allows proper classification of approximately 88 percent of suspects (Stuster and Burns, 1998). HGN may also indicate consumption of seizure medications, phencyclidine, a variety of inhalants, barbiturates, and other depressants.”

Walk-and-Turn (WAT)

This is commonly known as “walking a straight line”. “In the Walk-and-Turn test, the subject is directed to take nine steps, heel-to-toe, along a straight line. After taking the steps, the suspect must turn on one foot and return in the same manner in the opposite direction. The examiner looks for eight indicators of impairment: if the suspect cannot keep balance while listening to the instructions, begins before the instructions are finished, stops while walking to regain balance, does not touch heel-to-toe, steps off the line, uses arms to balance, makes an improper turn, or takes an incorrect number of steps. NHTSA research indicates that 79 percent of individuals who exhibit two or more indicators in the performance of the test will have a BAC of 0.08 or greater (Stuster and Burns, 1998).”

One Leg Stand (OLS)

“In the One-Leg Stand test, the suspect is instructed to stand with one foot approximately six inches off the ground and count aloud by thousands (One thousand-one, one thousand-two, etc.) until told to put the foot down. The officer times the subject for 30 seconds. The officer looks for four indicators of impairment, including swaying while balancing, using arms to balance, hopping to maintain balance, and putting the foot down. NHTSA research indicates that 83 percent of individuals who exhibit two or more such indicators in the performance of the test will have a BAC of 0.08 of greater (Stuster and Burns, 1998).”

“These tests are administered systematically and are evaluated according to measured reponses of the suspect.” In other words, the police are well trained in DUI detection. Approximately 50% of all arrests are DUIs. That means that DUIs is what the Police mostly do! In California there are over 100,000 DUIs each year! The three combined tests, called the 1998 Stuster & Burns tests, allow officers to be approximately 91% accurate in detecting a drunk driver! However, another way of looking at this is that 9% of DUI Field Sobriety Tests are wrong!

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