Police conduct various field
sobriety tests, but only three tests have been standardized by the
National Highway Traffic Safety Administration (NHTSA). Here's a
rundown of the three:
Horizontal Gaze Nystagmus
(HGN)
In an HGN test, the driver
is asked to track a moving object, usually the police officer's
finger or flashlight. An impaired driver would normally find it
difficult to track the object because the nystagmus—involuntary eye
movement—happens at lesser angles. Police also use the HGN test to
find out what kinds of drugs the driver may have consumed.
Walk-and-Turn (WAT)
The WAT test is one of two
divided attention tests (the other being the one-leg stand test)
where the officer instructs the driver to perform simple physical
actions. Usually, the driver will be asked to walk on a straight
line, heel-to-toe. A driver with a blood alcohol content (BAC) of
0.08 or higher may commit more than one mistake (e.g. falling down or
balancing with arms).
One-Leg Stand (OLS)
The OLS test, as the name
implies, requires the driver to stand on only one leg and lift the
other six inches above the ground. The driver will also count while
performing an OLS for 30 seconds but starting at 1,000 (i.e. 1,001,
1,002, 1,003). Just like the WAT test, committing two or more errors
suggests a BAC of 0.08 or higher.
The combination of these
standardized field sobriety tests accounts for an accuracy rate of 91
percent, according to studies.
The law firm of Kurtz
& Blum vigorously defends their client's rights. To contact
a Raleigh lawyer please call 919-832-7700.
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