Field Sobriety Tests or SFST were developed over the years to determine if a citizen’s natural coordination is impaired by drugs or alcohol. The tests have evolved over the years to the three current tests which NHTSA recognizes. The National Highway Traffic Safety Administration maintains that if the SFSTs are properly demonstrated by the police, that they can be an accurate measuring post of one’s level of impairment.
The present tests include the HGN or horizontal gaze nystagmus test. This is an eye test where the officer has the citizen track his pen or fingure as it is held 12-15 inches from the citizens nose and moved back and forth across a level plain at eye level. If the eyes fail to move in a slow consistent fasion, if they demonstrate “involuntary jerking” they are said to show nystagmus and therefore the presence of alcohol or some other drug. Unfortunately, following an exhaustive medical review of causes of nystagmus, the courts and the medical journals have also determined over 38 other causes of nystagmus as well. Maryland recognizes nystagmus as a possible test to demonstrate the presence of alcohol only- not the degree of impairment.
The second test is the walk and turn test. This is where a citizen is asked to take nine steps on a line, heel to toe and then make a strange turn and walk nine steps back. The NHTSA manual says this test is supposed to be done on a straight line, many times the police will have a person walk on an imaginary line on the side of a busy street, at night, in the dark. When a person fails to walk perfectly heel to toe, or steps off the line, they are considered impaired.
The final accepted test is the one leg stand (OLS). In this test the citizen is requested to raise one foot of the ground approximately 12 inches and stand there, count to thirty out loud without stopping. If the person raises their arms, sways, or puts their foot down, they are considered impaired.
These tests as a whole are supposed to reflect on a persons level of impairment. These natural movements, which people hardly if ever perform in their life, performed under duress, in the dark on the roadside are supposed to reflect on one’s level of alcohol or drug impairment.
My advice, don’t do them. There is no penalty for electing not to engage roadside gymnstatics other than having the officer threaten to arrest you- which he was going to do anyway when he smelled alcohol on your breath. Now your just giving him more ammunition to use against you in court.