Vegas DUI Defense Center: Attorney Jerry Donohue

The three standardized field sobriety tests are designed to be barometers for the patrol officer to judge whether or not a suspected DUI driver may be at or above a 0.08 BAC.

There are two balance tests: the One Leg Stand and the Walk & Turn.

These tests are designed to test an individual's balance.
However, these tests are not very accurate because many people have less than good balance for a wide variety of reasons. These include head trauma, foot injury, leg injury, inner ear infection, obesity, old age, being sick, being tired, and many more. Each of these tests has over a 30 percent false-positive failure.
That is, more than 30 percent of individuals who "failed" these tests in the government's study did not have a BAC greater than 0.08.
And besides, what does the ability to walk a tightrope line or stand for a length of time on one leg have to do with being able to drive a car? It certainly does not take balance to sit in a seat and drive.

The other field sobriety test is not a balance test, but a test of the workings of involuntary muscles in your eye sockets.
The Horizontal Gaze Nystagmus (HGN) test is designed to see if the suspected DUI driver has enough ethanol or some types of drugs in the blood to cause nystagmus — an involuntary twitching of the eyeball.
However, this test has its flaws because approximately 18 percent of the population has nystagmus when they are stone-cold sober. There are over 40 types of nystagmus with many, many causes.
Plus, some people will show nystagmus with a BAC of only half the legal limit. That is why the HGN test also has a high false-positive rate of approximately 28 percent.

So, failure of one, two or all three of the standardized field sobriety tests does not mean that the suspected DUI driver was illegally driving under the influence.

But, unless you hire a True DUI Attorney in Las Vegas, you will not have an attorney who fully understands the shortcomings of these tests.
 

Only a true DUI attorney can show the judge that failure of these tests does not mean that the accused was impaired or illegally DUI.