Standardized field sobriety tests – What are they and what are they looking for?

Before you’re arrested for a drunk driving offense law enforcement will typically ask you to complete a series of standardized field sobriety tests.  The three tests most commonly used by law enforcement in Wisconsin are 1) Horizontal Gaze Nystagmus (HGN); 2) Walk and Turn; and 3) One-Leg Stand.  Although officers may throw in a few non-standardized tests, the above three should be used and are recognized as being most accurate by the National Highway Traffic and Safety Administration.  So, what are the field sobriety tests and what are police looking for?

Horizontal Gaze Nystagmus

The HGN test has been shown to the be most accurate of the three tests.  The test has a 77% accuracy rate in detecting when blood alcohol levels are above .10%.  Nystagmus itself is involuntary jerking or bouncing of the eyeball.  The jerking or bouncing makes it appear that the pupil is being pulled back towards the center of the eye opening.

Nystagmus is caused by a few things, the most relevant in this case being alcohol use.  Certain other drugs that depress the central nervous system also cause nystagmus.  These substances make it more difficult for the brain to properly control the eye muscles.  As the concentration of specific drugs or alcohol increase in the body, the most obvious the nystagmus becomes.

The test is conducted by an officer who positions an object, usually a pen or a finger, a foot away from the driver’s face.  The officer then moves the object from one side to the other while focusing on the driver’s eye movements.  If jerking occurs before the officer reaches a 45-degree angle, it indicates a possible blood alcohol content above .05%.

A few of the biggest complaints about the HGN test are based on the fact that police officers are not medically trained professionals.  They also often fail to properly conduct the test, which results in a flawed test result.

Walk and Turn test

The walk and turn tests, when administered properly, is 68% accurate in identifying blood alcohol content levels of .10% and above.  The walk and turn test is relatively simple and is comprised of two parts.

The first part of the test begins before the driver even beings the walk and turn.  The officer instructs the driver to stand in an instructional pose – the driver is instructed to stand with one foot in front of the other in a straight line, with the heel or one foot touching the toes of another.  If the driver fails to follow officer instructions, such as standing in a “normal” pose or by beginning the test early, it is counted as the first sign the individual may be intoxicated.

The second part of the test is when the actual walking begins.  During the first part, the officer had already demonstrated how the driver is to walk along the straight line.  The officer tells the driver to take nine heel-to-toe steps down the line.  After the ninth step, the driver must turn around by taking a series of small steps and return to the starting place by taking another nine heel-to-toe steps.  While making each of the nine steps, the driver is instructed to count each step out loud.

There are a few clues that the officer looks to in the walk and turn test.  Again, starting early or breaking the instructional stance is one.  An inability to stay balanced during instruction is another.  Failure to touch heel-to-toe, stepping off the line, using arms to balance, an improper turn, or making the incorrect number of steps are all clues to intoxication that occur during the test.

The test needs to be performed on a dry and level area to prevent the surface from interfering with the test.  This is one of the ways officers fail to conduct the test appropriately.  As you know, Wisconsin winters can be long and snowy, and roads are often full of salt.  That could be a problem.  Wearing heels?  If they’re above two inches, you’re allowed to remove them.

One-Leg Stand

The one-leg stand test is third of the standardized field sobriety test battery.  It’s the least accurate of the field sobriety tests in this article.  When conducted properly it’s 65% accurate in determining whether the driver’s blood-alcohol content is above .10%.

This test is also the most simple, but it’s important the officer properly instructs the driver.  The officer, during the instructional phase, tells the driver to stand with his feet together and arms at his sides.  Often this is when the officer demonstrates the test.  Then, the officer tells the driver to keep his arms at his sides and raise his leg approximately 6 inches off the ground.  While keeping his leg raised, the driver is instructed to begin counting upwards from one thousand.

The officer looks for four clues during this test.  Swaying while balancing, using arms to keep balance, hopping with one foot to maintain balance, and resting the raised foot on the ground are all clue the driver is intoxicated.

Just like the walk and turn test, this one must be performed on dry, hard, and level land.  Again, if an individual is wearing heels, she is allowed to remove them.

What’s next?

Field sobriety tests are designed for the driver to fail.  Once the driver is to the point of actually doing the tests, the law enforcement officer has likely already made up his decision to arrest.  Should you succeed, you will likely be released.  If you fail, you will probably be asked to submit to a preliminary breath test.  If the preliminary breath test comes back at or above a .08 (.02 in some cases), you will be arrested for OWI.

At your first opportunity, contact a drunk driving attorney like Matthew R. Meyer to discuss your case.  Certain important timelines (such as 10 days to request an administrative suspension review hearing) must be complied with to preserve your rights.  Meyer can be reached at all hours at (414) 270-0202.